It's true in the Éa mod because the AI continues to look at cost/benefits based on what it already has. So,
- Lot's of fish -> AI targets Fishing tech for the sake of food
- AI has Fishing -> AI more likely to target Sailing because that would give it a name (a mod-specific goal) and it already has the prereq tech (making the cost for Sailing less that it would be otherwise)
- AI achieves Sailing first and becomes the Fomhóire civ, allowing it to cross ocean (civ-specific trait).
- AI can cross ocean so goes all Naval Expansion.
In truth, #4 isn't there yet. But #1-3 are in and working. There are also "scripted" tech/policy strategies that the AI can pick from, but again these are picked based on conditions (both initial and contingent), so allow differentiation based on how the game develops. Another thing that helps differentiation in the mod is a very "wide" tech tree.
If above concepts were applied to base, you would have emergent naval powers, horse-raiding civilizations, etc., that fit the natural geography. This is the way I've always wanted Civilization to work ever since they first introduced Civ-specific traits (was that II or III?). Hence the mod.
Honestly I think that having hard(ish)coded flavors makes the game more interesting. If you are playing against Alexander you should be at war all of the time for instance. Maybe in Ea it should be an issue of saying 'leader X wants to become a horse-lord, therefore he/she aggressively pursues horse resources on the map'.