Yes, that's a problem: Old users with high reputation abusing their power to edit other people's questions and answers.
Personally, I find it distasteful when somebody other than the question or answer's original author makes a substantial edit. Edits by third parties ought to be to fix typos, fix bad code formatting, improve clarity and the like.
One of the main points of the editing system is to fix the biggest problem with Q&A sites before SO - outdated information. Editing other's posts means that content can get updated, even if the original poster isn't around to curate it.
Everyone I've heard hating on StackOverflow are people asking or answering, who have ownership over their questions and dislike the rules or way the site works. The reality is that SO knows 99% of it's users never register and are reading answers, not asking or answering questions.
The reason SO is a great resource is that the rules create an environment that doesn't allow cruft to build. Yes, that puts off some people, that's a worthy trade in my mind. I'd rather have good content than more content.
> the biggest problem with Q&A sites before SO - outdated information
Post a new answer.
> ownership over their questions
As long as my name is attached to a Q|A, and my reputation is the one that is affected by its up and downvotes, I feel I have the right to control what the Q|A says.
> dislike the rules or the way the site works
I like the site's premise: Contribute questions and/or answers, and earn reputation if the community judges them to be good. What I don't like is that other people can affect my reputation by changing what I said. It's even more distasteful if the one who asked the question has also posted an answer. If the question wasn't clear, the first thing one should do is ask the OP to clarify. Only if the OP for some reason can't (e.g., if his English skills are lacking), then could the question be edited by a third party.
People reading the answers are more important than those answering - there are a lot more of them. Sure, people answering provide the valuable content, but most are not put off by the editing as you seem to be - if an edit is made, it is clearly marked that it has happened and can be reverted if wrong. The answers are wiki-like, and that makes the content better.
You may not like it, but why would StackOverflow change their system to make the content work to please a tiny minority of their community? It's a bad idea that would make the site worse.
Personally, I find it distasteful when somebody other than the question or answer's original author makes a substantial edit. Edits by third parties ought to be to fix typos, fix bad code formatting, improve clarity and the like.