I am going on with Sandii, Crawler, and Maurice for this. I do not think it's necessary to delete ones account because they didn't log in for a long time. Not most life is easy as it it maybe looks. And it's inappropriate to call them 'useless' just because they don't join conversations and things and such. They have things more important... Maybe they prefer just to lurk rather than joining in conversations (like most people). Doing so (deleting accounts), makes DCW more unwelcome. If I were to be a lurker and read this... I will be offended.
I know some quite people that they had joined long time ago and just has been active recently.