I read the parent post as a plea for better tools to filter that, more than a rant on the type of people coming in. Users might or not get better over time, and as you point out they may have a completely different expectation of the site.

I think it's a good tradeoff to let these users run free on lax subreddits and moderate heavily on others, provided the moderating tools get better and make it easier on the mods.