The same thing happened to me a while back, and someone showed me the [SOLVED] thing too. 
I think its cool, because it makes it easier for new-comers to search the forum for good answers, and for those looking to solve an open issue its faster to find a good target.
Yeah, ofc. Maybe they should add such a button to mark topics as solved 
There has been some discussion about various forum features lately, including exactly that, but I think it boils down to a template provided by 3rd party, so options are limited to some degree beyond monogame teams’ direct control.
-That’s actually the reason I brought it up in the first place!