The block feature is a good tool for people who are abusive and harassing. No one needs to suffer trolls only looking to ridicule others. But I agree, if you disagree with a person’s opinions or politics, it’s easy enough to simply ignore them—don’t read them.
Medium also allows you to select, “Show fewer stories like this” to see less of specific topics if you find them upsetting or uninteresting.
There is little civility online. Anonymity empowers people to be mean and “speak” in a manner they would likely never do in person (except on cable news.) So civil debate online is rare. It’s more one-sided ranting than anything.
Fortunately, I have not had to block anyone (yet.)