Maybe lets just delete accounts that are not active for, for example, 1 year ?

Its obvious that account owner has abandoned it. This could prevent forum from situation, when suddenty inactive account awakes and starts giving merits for strange posts.

From my point of view, all the long time inactive accounts are left for

1) merit selling in future
2) will be used as a high rank scam bounty topic starter (people will trust more to Sr.Member, than to Cooper member)
3) will be used for any other kind of scam promotion
4) will be sold or are being sold atm on different webpages/forums.