Not even close, it really irritates me when people constantly say there is something so much better to do and stop wasting your time. My mum always used to complain I watched too much football, but then what should I be doing. people generally interpret what THEY enjoy as worthwhile, everything they don't like doing is a complete waste and they just have to tell people that.
If you speak to people on an MMO, you're still speaking to them, same conversations you can have with anyone else, if you enjoy it more, all power to you. Frankly I go through periods of playing Lotro, and then being burned out/completely bored by them, but who the hell does it effect but me. Currently I'd prefer to play wow for a few hours than have the same damn conversation about the drunk weekend that just happened, because by and large its the same crap every weekend and the same conversation about the weekend following it. I'll then go through the polar opposite a month later and prefer going out.
The fact is if this guy is just happy playing the game, theres no problem, if he's lazy, getting rid of the internet isn't a bad idea, generally people who go from not working at all, to needing a job will be starting off with temp work, or some job in a store on a till, its still best to go in and ask for jobs at those places and get an application and will help get him out the house and moving.
if he's actually depressed, really any level is bad and you shouldn't just cut off the only thing he enjoys, its truly woeful advice. If he is ill in any way, physical or mental, get him help, and help him get HIMSELF out of his current situation. Don't force change on him unless you're prepared to make him even more depressed and the consequences that can bring.
Sabotaging his computer, not only does it sound stupid, childish and so stupendously easy I can't imagine needing to go on a forum to ask how, its a ridiculously bad idea for trying to "fix" his situation. When did everyone just get so, stupid?