I agree that to an extent people that trying to write a strong woman tend to try and make her like a man. They beat the reader over the head with how much better than the boys she is, or how them men feel threatened by her to constantly remind the reader that she's strong. It's as if they don't know how else to show the readers that this character they've written is strong, or are afraid you forgot it since the last page where they showed you.

The other way writers seem to try and reinforce the fact that the woman is strong is by constantly making her reject things that are traditionally feminine. It's like the writer is constantly screaming at you 'Look how much of a tomboy she is! Look how different from other women she is!' It's combating a stereotype with another stereotype.

Needless to say this can quickly get irritating, as good literature tends to be more subtle than a sledgehammer. But using these methods is easier than writing a female character that likes ribbons and unicorns and will beat the tar out of you if you dare to hurt the people she loves.