I flagged these two answers as not an answer:
This was posted as an answer, but it does not attempt to answer the question. It should possibly be an edit, a comment, another question, or deleted altogether.
I thought these answers didn't add much on what was already said, are not documented and could have just been comments (personnal opinions, "it's obvious"...). However, my flags were declined with the reason :
declined - flags should not be used to indicate technical inaccuracies, or an altogether wrong answer
I did not mean to indicate technical inaccuracies or a wrong answer, I simply wanted to indicate a "comment" answer.
Did I misunderstand how to use these flags?
EDIT: comments here and SS.'s one suggest to use the low quality flag but I can't see it: