If this was to stop potential account farmers, and people who later shit post to claim the potential activity from their newly bought account. Awesome job theymos

If this was to stop spam from yobit/bitmixer/betco/bit-x or any upcoming signature campaign participants, that uses Bot for managing campaigns. This won't work.
1) The bots use Last posts, to calculate post count and pay
2) They won't change it as they are getting their signatures displayed in those sections.
3) If they did want their participants to not spam, they'd rather block the sections themselves.

And this implementation will also have some downsides. Will this have a effect on past posts? I'm pretty sure most users will lose most of their activity. Also users like Xialla, many of the mods and current trusted members will downgrade to a lower rank