Next to "Please provide logs / system info bundle", "please mark the solution" is a common post.
Often the author of the "please mark the solution" post is someone with elevated forum privileges so why they can't just mark the solution themselves. In many cases, the OP has acknowledged that the solution is valid but they didn't mark it, so why can't someone with privileges do it for them?
There will probably still be cases where the OP really should be the one to do the marking, but there are many more cases where just doing it would make for a cleaner topic.
Good point. I hopefully just changed the configuration so that anyone TL3 or higher can accept solutions. Mods and admins already could do that (and I've also done it in the past).
I think auto-closing straight after solved is a bit too soon - there's definitely legitimate follow up questions, maybe the problem comes back later, or even a simple 'thanks for the solution' - blanket closing threads will not fit everything.
Topics will auto-close after 3 months of inactivity, so if the solution has been found then the topic will close after giving some time for further discussion