And 60-70 years ago there was no such thing as protected groups. Businesses could and did deny service to anyone for any reason. Collectively, we as a society looked at that situation and said "Hey this isn't great that businesses can deny service to whole groups of people based on their religion or skin color, we shouldn't let them do that", and we stopped letting them do that.

Similarly, today we can look at what's happening and say "Hey this isn't great that businesses are allowed to restrict our speech and narrow down the realm of ideas to the least common denominator. It is destructive to the public discourse that a small group of people can claim outrage and shut down whoever they want", so we can decide not to let businesses do that, just like we decided not to let them refuse service to protected groups.

Is public discourse being wittled down? I can buy books from across the political spectrum within seconds. Consider Jim Crow versus not being able to buy a physical copy of an obscure book that can still easily be found online for free