To multi-log.. hmm.. I'm guilty as charged of such a thing.
Now let me tell you, it's HARD! Do you know how ridiculously hard it is to keep two game clients open at the same time AND do a semi-afk-able task? That's just with TWO clients, imagine three or four, that would be nearly improbable on all levels. Not to mention the task each one may be doing! I was just woodcutting, imagine firemaking, runecraft, combat, etc, it's just ridiculously unlikely.
All in all, I say let it stay. If people want to do it, let them, they're the ones who have to suffer with being bogged down by having multiple clients open, and skilling/combat/etc. It's annoying to attempt, and annoying while in progress, and overall I doubt we'll ever seen it being widespread.