I've been saying this for at least 20 years. As each Age of Man progresses, the focus shifts out more. So starting in the stone age focused on the tiles around you, and ending in the space age with the focus on our immediate zone of the solar system.
Rather 30 years.
Today it seems to me as if such ideas were already seeded in the community's civ2proposal
collection -- though I have to admit, that it has been a REALLY long time since I visited actually that file finally maintained by Jonathan Buckle.
The longest time I thought, this would be just a great way to design it; now I think, it is the only possible way to implement it (for balancing reasons). I hoped, the players would anytime understand and accept, that a game 1) long and 2) with rich detail NEEDS phases of (real) setbacks (aka negative feedback) to be stable and balancable at all. But players don't want to be punished for playing well
-- no great idea of Rise & Fall! Sid explained this well in videos, but the solution to make therefore only short civRevolution games felt not so satisfying to me ... so welcome back to the machine
, ahem, late game boredom. Civilization is most successful, but still too long.
In OldWorld people accept, that a new ruler is weaker than the predecessor was; even expect it. Continuing details (family, cities, neighbours ...) grown fond of in a new setting of different game (normalized strength, new era, new rules) might not be experienced as punishment (alike beginning a new set in a tennis match at zero).
2 millenia of progress cancelled
We are so used to the "exact" development path we took!
In Francis Tresham's Civilization board game (covering only antiquity) there was no tree: all techs could be bought from the beginning -- cheaper ones (with smaller effects) affordable earlier and stronger ones more expensive, later.
I like how OldWorld handles this with the cards deck. From a gameplay pov ... (Anton's tech shuffle mode was for me the best one of civ6NFP).
And because there is by far more randomness to development than a tree suggests. For a discovery being established and not soon being forgotten again it depends a lot on accessibility of the raw materials (eg. near eastern crude oil in case of the Greek fire of the Byzantines) and the opportunity of broad usage: ?Electricity in ancient Persia: earthenware vessels within copper and iron rods isolated by tree resins -- ie. a battery, could be used for galvanisation ... perhaps in turn leading to Archimedes' Eureka!
// Heron of Alexandria / Vitruviusˈ steam engine