The whole problem with all of this is that the amount your ranking increases / decreases by is determined by your OPPONENT'S rating, which means that whenever I face someone good on a fresh alt on the ladder, I win jack shit when I do win and lose a ton of points when I lose.
A "Reset Ladder Rating" system wouldn't help either. Now I'd be able to know if I'm playing someone really good, but their ladder rating will still be in the shitter, and then we're back in the same boat.
I think that the alt problem is just part of a larger problem: namely, the fact that often a player's ladder ranking and their skill don't even come close to corresponding, so it's easy to abuse it and reset your rating by making an alt, which utterly fucks most everyone else around. While I believe that alt accounts should be banned, they're only one part of the real problem, which is a system that results in flawed and inaccurate rankings and that rewards alt use.
Glicko-based rating systems only work when the ratings that are given to players are actually accurate. Allowing players to reset those ratings through a "reset ratings" button or the use of alts ruins this, as you get a ton of skilled players with extremely low rankings fucking up the system. Either alts need to be banned AND rating resets need to be disallowed, or the ranking system needs to be revamped to take into account the fact that there is a high likelihood that there is absolutely no correlation between player ranking and player skill.