Specifying characteristics of exemplary people, can serve as an encouraging example for others with those characteristics. Maybe another potential future female founder will read about her example, and decide to pursue the same path. Not everyone needs that, but sometimes it helps.

Mentioning the female gender (I am assuming cis-gender sex/gender terminology) is an identifier that points to the added difficulty of starting a company in a culture where women are treated as inferior or have less social power. So they're pointing out how the company was created under potentially difficult circumstances. The idea that it's difficult for women to start companies turns gender into a kind of 'selling point', as in, because this company was started by a woman, it's clear the founder must have extra-ordinary abilities to be able to survive in a culture that often treats women as inferior, and this company may have properties that make it "better" than any other average company not started by a woman. So gender mentioned here is not only falsely attributing greater business acuity to the company, it also acts as a PR flag to attract attention to the company. People therefore perceive it as important that the founder is female, hence mentioning it in the title.

It's only relevant because in today's startup environment, "single female, non-tech, no-team" is considered an outlier regarding the characteristics of a successful (subjective) founder.

That's the real question. It's not like being a female is a handicap or something.

Gender Baiting. It goes along with the whole Silicon Valley is Misogynistic theme.

Why is it not?