I think but don't really know that people, in this case, writers chose the 'Buy me a Coffee' app because it appears better than other similar apps. From a user's (reader in this case) pov I prefer the similar app 'Ko-Fi' because it's a better app experience, again, my pov. To me, it's just easier or less unnecessary usage friction.
Having said that, again, yeah, I've used both apps inside Medium. I like to be able to help gig workers that really know their work including putting out work when they can and yes, also tickle my neurons.
When I was younger I never had to put up with the kind of employment environment that today's workers exist in, this whole side-hustle-gig thing. It was next to nothing to find work. Not today, I don't think so, no matter how much jolly noise is out there quoting statistics about workers and their employment status.
So I think the economy is not cutting it, and in that little way, we can help when we can.