In aoe4, it looks like every civ has access to every generic tech and unit upgrade, with unique techs, units and civ bonuses layered on top. This is a major change from aoe2 where every civ is missing some amount of the base techs and upgrades, and has less (in number) civ bonuses.
I think having the game work this way is great, since it is overall much easier to remember the ‘extras’ than it is to remember any removed parts. every civ has access to, at the worst, ‘generic’ versions of every military unit fully upgraded.
I think there is also a psychological aspect to this too, since players will be thinking positively about the bonuses - “I can do these couple of things better” instead of about penalties - “I can’t do this thing that everyone else can” and this will hopefully lead to more diverse games.