Yea thats fine for short-term rate-limiting defense against DoS, but doing anything reputational with IP's beyond that will hurt new users even worse in the long run

Tiering works well in many environments, for example you can still allow new users with no friction but also impose a basic rate limit (or kind restrictions), with upgrades to those permissions achievable either via a PoW flow, WoT-invite flow, or just good behavior heuristics over time