So many times, the person who opens a topic in a category like support doesn’t know to click the ellipsis and mark a post as the “solution”.
It would be nice if anyone could use the “solved” checkbox as a way to easily let the OP know they should consider marking a post as the solution.
Keep in mind the person who opened a topic does not need to click the ellipsis - the solved icon appears right next to the like button.
I updated my post 
It also occurs to me that if they participate mostly via email, the note/reminder would be there waiting next time they log in.
To take it a step further… perhaps in a category with the Solved plugin enabled, discourse would ask the OP if their issue is solved X days after the last post?
I’m getting flashbacks to Stack ExchangOverflow, and various attempts to encourage people to accept answers on their questions… from memory, every attempt in that direction fell foul of the simple problem that nobody likes to be told what to do, and hit-and-run posters aren’t going to come back to see your admonition anyway.
There are settings to allow admins, mods, and various other high-value personages to tick “solved” on a post, and I think that’s about the best you’re going to be able to get.
We do this quite a lot on one of my sites. I’d say 80% of the content is “questions” or “issues”, and our mods are quite quick to mark topics as solved. We only started using the solved plugin this year, and we’re starting to see more users mark their own topics as solved. I think it’s just a matter of reaching that “critical point” where people know what “solved” is, and they start using it themselves.
I think sending a “Did you find a solution to your problem?”-reminder would go a long way towards solving this issue.
I was thinking as much about here on meta as much as on my site. The consensus seems to be “it’s good enough as is/nothing is likely to work better”. which is fine by me.
See Automate reminders to mark solutions feature request