I didn’t realize how bad it got until my father stopped answering calls. It turned out he was getting (no hyperbole) 90 calls a day from spammers and vendors he had no relationship with.
I used the iOS filter, the AT&T filter, and turned on the shortcut so the phone doesn’t ring unless the caller is in his contacts.
The problem is that it already changed his behavior. He doesn’t answer the phone anymore, even if it is a person he recognizes. The Pavlovian response to his ringtone is still very negative.
I’m sure there is a non-trivial percentage of the US who already viscerally hates receiving phone calls.