It's a game which defaults to randomly generated maps. By the rules of alternate history, that literally puts the point of divergence for your alternate history several billions years into the past, back when the Earth was a molten ball. Assuming any of what we know about history remains true with a divergence that early is actually a violation of even the most basic rules of althistory - there shouldn't even BE greeks or romans or *anything recognizable at all* on a planet like that, let alone greeks with recognizably greek cultural traits. In all likelihood, recognizable humans are a dicey proposal at best on a planet like that - different landmasses with different connections, and the possibilities that mass extinction events happen at different times or not at all (I don't see the Chicuxclub crater on my Civ maps, do you?) lead to a situation where even the very basis of what species are alive or not are completely impossible to predict.
Even if you DID use a real world map in Civ, and used True Start Locations - that would still put the point of divergence in 4000 BCE, when the game begins - 3500 years before the heydays of Greek city-states. That's (considerably) more than enough time for history and Greek cities to evolve in a completely different direction, and never form the propension for independent City States we know them to have had in the mid-first millenium.
For althistory to meaningfully resemble our own (eg, recognizable culture, civilizations, etc), the point of divergence has to be reasonably close to the start of our story. That definitely doesn't happen when you have a random map, and it pretty much doesn't work either if the history you want the game to replicate is several centuries or millenia after the point of divergence.
But Civ is not a althistory game. It's a 4X game, and the random map is a fundamental part of that (because the first X is exploration, which implies a world that is unknown to players at game start, at least by default). It is, to all practical purposes, a fantasy map populated with cultures loosely inspired by real world cultures - which it has to be for random maps to work.
I'm sincerely not certain if this is a
reducto ad absurdum argument or a simple lack of geographical knowledge as it applies to a 4x game based on modern human populations.
First, any game that starts, as you seem to indicate, long before anything resembling modern humans are on the planet, is no longer a historical game at all and so outside any discussion in this Forum. (also, if you're going back that far Why Stop? Might as well go back to the Big Bang and start with a real 'blank map')
Second, for as long as modern humans have been around, and most definitely by the beginning of the Neolithic, both the climate and its effect on the map and the terrain on the map itself have been in near-constant Flux. Go look up the African Humid Period, the Khyalynian Sea, Lake Ojibway Collapse, Little Ice Age, among others. In addition, humans themselves have been modifying "the map" for at least as long, using fire and other techniques for changing the flora and fauna to their own ends even before sheer numbers of humans starting to have a major effect in the past 1000 years.
In short, even if you assume that the map is the sum total of Civilization divergence (which, despite Jared Diamond's arguments, is still very much debatable) the Map Is Not Static and so the geographic conditions change from whatever date you desire to start the game (but, please, keep it since modern Humans appeared unless you want to change the game from 4X to Anthropological Determinism) so that any group on the map will/should have to deal with a changing map, not a set of static conditions.
And yes, at the traditional 'start date' of 4000 BCE for Civ, none of the 'Civilizations' in the game exist in more than prototype form - and that only in Egypt and Sumer, with a number of caveats. In fact, most of the peoples that will become the later Civilizations aren't even anywhere near their 'starting positions' yet: the 'Greeks' are not only about 2500 years in the future as recognizably Greek but at least 1000 kilometers off to the east with a different language and basic food supply, and religious practices which can only be guessed at from archeological evidence.
I submit that is not an argument for being content with a set of fantasy starting Civs, but for making a game that shows the development of those Civilizations from far more different 'starting points' than the game provides now.
The
Humankind game appears to be 'dipping their toe' in that water, by starting with a Neolithic Era in which you do not play as any recognizable group: you choose your 'Civ' (Faction) only when you achieve a progression to the Ancient Era. Add to that some influences (but NOT absolute ones, or the game becomes an attempt at Geographical Predetermination or Historical Simulation, and even I don't want to play that!) from the terrain and climate and maybe even some 'preliminary' cultural/civic traits, and I think it would be a major step in the right direction.