I think a 30 day limit is far too restrictive. Imagine making an account to ask for help and then being told you have to wait 30 days. You’ll just turn to reddit like the 99% did from the start. The fact I couldn’t help/answer people’s question on SO after signing up permanently turned me away from that network, just as as an example.

Most spam reports that reaches this instance is from other instances, so even with the wrong assumption that us putting up a restriction would block spammers, it would hardly put a dent in the amount of spam.

I think the real solution will be better moderator tools so that mods can effectively control their community as needed. An auto-mod can already do exactly what you’re asking for on a community level, which wouldn’t be as oppressive.