If you've ever ridden public transit, you've probably seen people sitting like this:
It's called "manspreading" — when some men in public take up way too much damn space.
Women — or, really, all people with some level of manners — have been complaining about this phenomenon for years. (The official name for it came about around 2013.)
It's not that people shouldn't sit in a way that's comfortable for them. It's that spaces like, say, the subway are public places, and taking up two seats with your legs spread apart is unbelievably rude and entitled.