Some users do not mark an answer as "solved my question", even though they leave a comment stating it solved the issue. For example this one.

What can be made about it? Can a flag be issued in order for moderators to mark as accepted? These type of cases seem to me unambiguous.

Ps: in my view this is not a duplicate of "force leavers" question, as my point is not directly about leavers (OP was active 6 days ago), and refers to questions where it is unambiguous that an answer solved the problem (via an explicit comment).