I do the same thing. Everytime a story with a topic I don’t want to read pops up in the main feed, I use the “Show fewer stories like this.” It really does make my Medium experience better. I also don’t follow anyone who writes predominantly on those topics. It’s not personal, I just don’t want it in my “New from your network feed.” On the mobile app it is under the “three dots” menu. It’s definitely worth the extra second it takes. After a few days of doing this the main feed improves dramatically for the better.