You're thinking far too hard. If I can ping 1.1.1.1, it means traffic is flowing from inside my network, to outside my network. I'm not going to diagnose my ISP's issues, that's their job, I just need to know that it's not my problem.

Most of my connection issues are between the street and my computer, I don't think Cloudflare got there. Yet.

You can have routing issues that alow some IP addresses to work and others not, anycast or not. It's not supposed to be a comprehensive connectivity report, just a sanity check that the intertubes are connected at all.

Of course. Ping 1.1.1.1 is not a test that everything is working great. DNS could be dead. IPv6 could be black holed.

But it’s a good “is traffic making it past my router with some semblance of connectivity” sanity check, and easier than finding the provider-side next hop address.