Because they provide a valuable insight that is currently being systematically ignored, which can allow businesses to meaningful engage with and provide useful services to a currently poorly serviced market segment.

I haven't worked at a single team without at least one woman, why wouldn't people just ask them instead of going out of their way to get more? I mean, if we reduced the amount of sexism then the voices which are already in the field would suddenly be heard and we would no longer have the problem you are describing.

All of my teams, at at least one point during my time there, had zero women in them.

One of the teams eventually had two women, but at that point six of the men shared a name with another team member.

Wow, really? That seems unusual - how are you defining "team"? I use it to describe a group of about 7-10 people and I have definitely seen many of them with no women.

20% are women in the places I have worked so you would expect there to be around 2 on average then. The probability then that a team of 10 has zero women would be around 10% so not that common.

20% is definitely higher than average, and higher than any company I've worked at. And you're assuming a completely random distribution, which is not the case in my experience, for whatever reason.