I really find the whole clapping system pretty weird too. Having claps anywhere from 1 to 50 is kind of crazy, right? I'm not sure I could have so many different levels of me liking/loving an article. I would think if I was going to give anything 5 claps I might as well give the full 50 haha.
I love that you brought up Pixiv's like and bookmark options (yes, the heart is actually for bookmarking, but clicking it basically means you love it). I think Medium would benefit much more from a simpler system like this.
Fun and interesting read :)