It actually does. Correlation is not causation. Bad writing/acting doesn't mean Mary Sue. She doesnt appear to have a weakness because she is Galadriel. Not because she is female. She is the niece of Feanor for fuck's sake. She is Finarfin's daughter.
"She is described as "the mightiest and fairest of all the Elves that remained in Middle-earth",[and the "greatest of Elven women".
"Fëanor and Galadriel were always unfriends, both being the greatest Eldar in Valinor;"
"Even though she was one of the leaders in this revolt, during the troubles that followed she fought fiercely against Fëanor "
Yeah.. Mary Sue indeed.