Do you need to pay to access Steam and play games? The answer is no - there are free games on Steam and also forum features that allow you to post media content too. From that standpoint they're in the same boat. The difference is the platform's intended use.
I think the real issue isn't about Visa and MasterCard trying to gatekeep/censor this. The talk should be about we as a society haven't matured enough to be willing to talk about our own bodies as humans and human nature with our own kids. If you look at what's shown on mainstream TV around the world, off the top of my head, Europe seems to be a lot more mature about it than many parts elsewhere.
This is a stupid made up wedge issue. The real question should be - what is sports and what exactly are athletes competing for?
Why is it the default in sports male and female categories? Is it because they are physically different? Is it because one has a uterus? is it because of hormones so males and females develop differently? We have managed, through scientific breakthroughs, hormone replacement therapy to be able to transform our own bodies into what we want and that in itself is an achievement - albeit it isn't perfect yet - but that's another topic.
If the goal is to compete and display human physical prowess and strategy in a regulated environment then male/female/other/etc. categories shouldn't exist. It should only be rated as 'where do I stand as a human being among my peers in X sport?'
Trying to fit a gender into a flawed categorical system of sports is bound to cause friction.