I'm not sure it's as much, but IIRC there is an IP registration limit. E.g. if you wanna play with a family member there is a chance they will not be able to register a new accound if you just did.
The AI is bit tailored to 0 A.D. new buildings and gameplay confuse it a lot. It's why Hyrule has their own version that only supports a handful of the civs and Delenda Est sometimes has trouble.