Well if I may venture my head above the parapet, there are as always two, if not more sides to this.
First, OPs often ask for advice or help on very complicated or difficult issues without a lot of information. Why we should feel able to trust complete strangers with something so personal is another matter, but it can happen that the OP subsequently adds further information which can cast a different aspect on the original problem.
So members ask questions, make suggestions and, frequently make judgements based on what they have read.
Some go to considerable length, often giving the benefit of personal or professional experience so it can be reassuring to know that OP has read that.
At the end of the day, nobody is forced to do anything, but there are times when it seems that the OPs have moved on, may not want further discussion of their issue or indeed that there has been a resolution of the problem.
If the latter, then there is no point in further consideration of the issue by members joining in later.
It can be a way if saying “Thank you for your input/problem solved/gone away/going to do my own thing whatever “ but the bottom line is that he or she may not want us going on and on about it.
Is that unreasonable?
There is of course the other sort of OP (not this one) where something quite contentious or shocking (or even banal) is posted and then we hear no more which can leave one wondering was this just to stimulate discussion? Just a bit of fun? (The onesie/plimsoll/school uniform/GD not allowed to go to the loo in school/ type of thread)
Just expressing opinion, not worried, Bluegal merely an observation.