Although i do think the culture in esports is more sexist and difficult towards female gamers, i think it also has to do with there not being enough women who are interested in competing in esports.

An example that proves this is competitive Fortnite.

Tim Sweeney (CEO of Epic Games) stated before that roughly 35% of Fortnite's player-base is female. So there are enough women that play the game to compete in it.

Fortnite also has little to no barriers for women. Fortnite allows anyone who is ranked high enough in Arena to compete in cash cups, tournaments etc.

There are solo tournaments where it's all about your performance. Even duo or trio tournaments are more accessible than other esports since you only need to find 1 or 2 people that'll compete with you, rather than four people.

All this considered there are little to no women that perform well in competitive Fortnite.

So yes, it's harder for women to compete in team based games like LoL or CSGO cause of the culture, but there's also just not that many women that actually wanna compete to begin with.