I didn't make myself clear.
I was not advocating a more complex system, but a difference emphasis within the system. Specifically, more emphasis on the in-game actions and events to influence Learning progress (since Technology is too easily confused with pure technological progress to the exclusion of social, civic or 'philosophical' changes, I'll use Learning as more generic term until someone comes up with something better).
I want to emphasize both the effects of having an illustrated need (by game actions) for an improvement in status and the Law of Unintended Consequences, where you think you are looking for a solution to A and get a solution to Z, a problem you didn't know you had. Examples are myriad, but two spring from nearly the same general historical source:
Alchemy in the west, expanding from the Hellenistic roots (another partial consequence of the Library/Museon at Alexandria, in fact) cpncerned itself with turning base metals into Gold. Consequently, it explored inorganic chemical interactions, wound up distilling both sulphuric and nitric acids, and by the Medieval Era (in the Caliphates) set the basis for future developments in Chemistry and Chemical Engineering, incliding smokeless powder, advanced chemical fertilizers, and modern medicines - none of which, needless to say, were what they were looking for.
Chinese Alchemy, on the other hand, was almost exclusively concerned with the search for Long Life or Immortality, and so had something of a Medicinal Basis from the start. Messing about with substances, they produced, according to the earliest probable mention, "three powders that fly and dance" - Fire Seed, or Gunpowder. Unintended consequences, indeed.
Part of this thought process is to find a way of making the Tech Tree less linear and more subject to variation within each game. Current attempts in this direction seem to be revolving around Random Card or Deck-draw and shuffle and other Gamey mechanics that, to me at least, simply intrude into the game.
So, for instance, taking Civ VI's 'Eurekas' and Bonuses, why not turn them around? That is, instead of the Eureka being a bonus to obtaining a given Technology, why not make them (with considerable revision) a requirement?
Example:
You don't have a city on the coast, you can't research Seafaring or Sailing. It won't even show up in 'your' Tech Tree for that Civ in that game. You might get it by diffusion from a neighbor (including, of course, a City State or Settlement) but that will take longer and how long depends on how much you have to Learn: if you live in a desert without forests, you won't even have the woodworking skills to build hulls, let alone make sails, rigging, and learn how to use it all.
By using the in-game situation of each Civ as a basis for what they can learn, each Civ's tech tree should appear somewhat different to each of them, and provide a variety of paths to 'progress'. Because, in addition to technological solutions to your situations, some offered solutions might be 'soft' solutions, like opening up trade with a landlocked neighbor across the desert instead of taking to the sea routes. Multiple routes to a goal or solution should almost always be available in some form.
Another point is to separate Knowledge from Application. Call them Projects: you learn how to build sailing craft or gunppwder, that doesn't instantly give you a massive Naval Empire or Gunners. For those ships, you also need docks/harbors of some kind, which means new ways of building with stone, brick, wood or concrete (waterproof mortar was actually invented before 600 BCE, for just this type of construction). The progress from Gunpowder to Gun took, IRL, at least 400 years of trial and error, through fireworks and firelances and exploding grenades and incendiary devices before they actually shot anything solid out of a tube using the 'flying and dancing' powder. This, in fact, might be where you have to concentrate Resources: call them Research Points, or Knowledge Infrastructure (build a Navigator's College, an Alchemical Laboratory, or just require every walled city to include Gunpowder weapons in its stockpiles - all were done)
Final Point: Every Civ will start with some 'technology', based on what they've been doing Before the Start. The way to handle this, I think, is to fiddle with the opening sequence of the game.
Right now, you pick a Civ (or Random), sometimes pick an Alternate Leader, then see the map and start playing.
I propose that you pick a Civ, see the map and your starting biome, and then pick from a set of offered technologies: Have a spot on the coast (or, possibly, floodplains full of marsh and fish) and you can pick Fishing to start, which includes primitive Boats. Start in a desert, and Woodworking will NOT be an Option.
I suggest, for a simple scheme, that potential Starting Technologies might be organized as:
Food Sources:
Animal Husbandry/Domestication - if your start includes Cattle, Sheep, or Horses.
Agriculture - your start includes Grains, Rice, Maize or any Food Plant as a Resource
Fishing/Boating - your start is on the coast or next to Floodplains/Marshlands
Building Materials:
Stoneworking - requires a Mountain or stone or marble resource in the starting radius
Woodworking - requires some kind of Forest in your starting radius
Pottery (brickmaking, adobe) - requires marsh, coast, floodplains in the starting radius
You might also pick a Project related to the Food Sources:
Brewing - a Project of Agriculture
Archery - a Project of Animal Husbandry
Weaving - a Project of Fishing (earliest man-worked fibers found were fishing nets from the Paleolithic)
I suggest the picks be made after your initial Settler/Pioneer move, so you have some slim choice about the starting position that will influence what you are offered. You have to choose a Food Source (and, for instance, you might frequently get one or more possible choices, if the terrain is coastal and filled with useful plants and animals) first, and then you can choose One more Project or Tech. If you don't choose any of the Building Materials, you probably aren't going to be building any early monuments, city walls or other substantial constructions, but you might have some very happy population (Brewing), early military/defensive advantage (Archery) or early Luxury Goods (Weaving)
Rather obviously, most of these will also give you a jump start for later developments:
The kilns required for pottery/bricks are also the ones used for primitive Metallurgy, the working of Copper, Lead, Silver and Gold
Stoneworking or Woodworking give you the option to pour effort into an early Monumental Construction: Gobekli Tepi, The White Temple, Tarxian Complex, Si an Bhru, Henges, Dolmans, etc
Brewing provides a bonus for development of Ecstatic Religion, Oracles, and Festivals - you mau have more social/civic choices earlier than your neighbors.
