Your reasoning doesn't stand. Not every film would be downvoted that had a female lead and this film is one of a few that attracted the anti-feminist brigade for reasons including:
1. It's the first Marvel superhero movie with a female lead and that is literally without precedent in a male dominated genre
2. Brie L is a vocal feminist, which generates a vitriolic reaction
The film may, or may not be, crap. I don't know. Even if I did have an opinion it would be subjective. For instance, the recent Ghostbusters remake, which was absolutely dreadful and deserved to be panned, was also targeted by the same groups of individuals. This doesn't change the fact that it would have had dreadful audience scores anyway due to the fact it appears to have been sellotaped together from unfunny improvisations rather than actually written and is in direct contrast to the very well made original.
However it is clear in this case, and there's plenty of evidence in this thread, that there are people who are downvoting this film, without having seen it in some cases, for reasons of politics.
Also, as a side point the fact that many women may not like this film is irrelevant to the points above, especially when said women are professional film critics who, in general, are not overly fond of superhero movies.