Thinking about it how about "rolling merit"
You need:
Brand new: Same
Newbie: Same
Jr Member: Same
Member: 10 but must get at least 1 every month or you drop to Jr. Member
Full Member: 75 but must get 5 every month on average per rolling 6 months or you drop to Member
Sr. Member: 150 but must but must get 7 every month on average per rolling 6 months or you drop to Full Memeber
Hero Member: 450 but must get 8 every month on average per rolling 6 months or you drop to Full Memeber
Legendary: 750 but must get 10 every month on average per rolling 6 months or you drop to Full Memeber
This way if you are off the forum for a bit due to work, life stuff, etc you are not dropped straight down to a lower member tank for months, BUT if have status you have to work to keep it with good posts.
And, even if you are legendary and you have an issue and have to leave for a year, in 6 months back of good posts your status is back
-Dave
This can create a FOMO. There may be accounts using purely for knowledge purpose and not for signature. There are member or even hero member accounts with no signature.
Instead, Why can't there be a relation between the number of posts or comments getting deleted by any account and its rank rollback. This will make them alert that they need not post any waste comment that can cause their account a threat.
I had read that there are lots and lots of comments getting deleted on daily basis irrespective of the rank the account is in.