Since a new user to Stack Overflow like me can only post an answer to a question every 30 minutes, this makes it extremely irrelevant for new users and will in short; drive users away from Stack Overflow.
It helps to limit spammers who would like nothing less than to post spam much more quickly than every 30 minutes. It is easier to clean up one spam post than 10.
Also some people just don't quite get the site when they start out. They answer off-topic questions or don't answer properly at all or ask questions in the answer space or add me too as an answer. We'd like to be able to catch and warn such people before they become answer banned entirely.
Anyway, the Stack Overflow limit would seem to be back to 3 minutes now that the worst of the ChatGPT wave is over. Proof this deleted answer and this deleted answer were posted approximately 3 minutes apart on 28th December by a user that almost certainly never made it to 125 rep.