Give me me 2 minutes, I'll tell you EXACTLY why this is a bad idea...
Reason this is a bad idea:
Leechers will turn to spammers. All leechers are here for are the hacks, when you put a post limit on getting hacks, you'll have leechers spamming some randomly place to get the 25 post he needs to download the hack. He will end up getting banned after he gets the hack, and when the hack get patched, he will sign up under another account and do the same thing and it'll just repeat itself. So let leechers do what they do best.....leech.