This is not false, but it's missing the biggest reason (probably accounting for 90% of the "why") and it's the level of performance. Has nothing to do with how long it's been played. The reason female soccer is not watched is because it's simply because they're inferior. When's the last time you watched a second league football? Or F2 race?

Female sports in general are lower caliber, making them less interesting to watch.

There are some exceptions though.

Female tennis gets a lot of exposure. Why? Because the sport is very different. The women are weaker in strength making the tennis exchange longer and to some, more interesting to watch.

Unfortunately you can't translate this to all sports, making some female sports simply not to par with male leagues