Most times, only OPs are the ones able to address the close reason.
That's one of those truisms that gets tossed around a lot... And ends up being more of a self-fulfilling prophesy as a result. Consider that there are multiple, distinct reasons for something to be reopened:
- It didn't need to be closed in the first place (voters misinterpreted the question)
- It did need to be closed, but the reason for closing it is no longer in use (for example: obsolete close reasons, or rules regarding a site's scope that change after meta discussion)
- It did need to be closed, but the problem has been corrected (by the author or someone else)
When folks talk about askers editing to address a close reason, they're usually thinking of category #3: it's easy to find questions that are missing details or specificity and cannot be corrected in good faith except by the person who needs the solution...
...but those are not why we have 3rd-party edits triggering a reopen review. That functionality exists primarily because of category #1:
See, closing and re-opening aren't exactly equal. Most notably, closing requires you to specify a reason - reopening does not. This cuts both ways: closing requires more effort, but other voters also have a reason they can either agree or disagree with; unless the person voting to re-open left a comment, there's nothing to indicate why he thought re-opening was a good idea.
Asking good questions is hard. Identifying good questions isn't all that easy either - and sometimes folks make mistakes there too. Sometimes an edit doesn't really have to fix anything so much as make it clear that the problem never existed in the first place. THAT'S where the third-party edit trigger becomes important.
The success rate when flagging for reopening is... Not great. The success rate when 3rd-party edits send questions into the reopen queue is even worse... BUT, it's a lot more accessible - anyone can edit, even folks who can't flag or who wouldn't think to do so. As a result, more questions have been reopened following 3rd-party edits since we implemented this trigger than have been reopened via moderator flags during the entire history of Stack Overflow... It's not doing a lot, but it's still better than what we had before.
The truth of the matter is, most edits don't result in questions being reopened. That goes for 3rd-party edits, but also for edits from the asker. I'd still love to hear suggestions for better guidance for editors, if anyone wants to propose some. "Better" here being guidance aimed at improving the resulting edit, not discouraging the editor from editing at all.