One of the main reasons I keep my subscription and remain part of the MPP is because I know when I read other writer's work at least they receive a tiny amount of money from me. It isn't much of course, but at least I'm support them a little bit.
It seems like for about 90% of writers on Medium it is basically a way to buy them one or two cups of coffee at Starbucks every month, lol.
I've been looking in to alternative sites like Ko-Fi and Vocal Media, but it is hard to say if they are going to be any different or better.
Maybe like you say, unless there is a profitable model for sites like Medium it is unlikely that anyone other than the lucky few or those that fugure out how to game the system are going to do very well.