It's that collective mentality of people looking down on others for preferring female characters. Someone can even have a preference skewed a bit more towards female characters but there's still likely more reasons why they like those characters, like personality, design, how they would fight, ability to connect with those kinds of characters on a more personal level, etc.
Or even aesthetic reasons. I personality prefer female characters most of the time cause I find it very difficult to be motivated enough to play characters that aren't aesthetically pleasing to me. Female characters fulfill that for me, and aesthetic is an important part of many people's character choices in fighting games, so I really don't understand what the problem is. That doesn't mean I like characters only cause they're female, cause they still have to have a design and personality that appeals to me aside from that.