Why is pinging an anycast address an issue? Most people, myself included, ping addresses like 1.1.1.1 to check for internet connectivity. It's a perfectly valid check, you don't need a fine grained test all the time. If it fails, then I go looking in detail. Most of the time it will pass.
Pinging a domain name could fail for a variety of other reasons, particularly if it's not a reliable site. Cloudflare's business is being reliable; few sites would be a better choice.
The problem is pinging 1.1.1.1 can end up hitting a really really close-by server. You could be having ISP issues and 1.1.1.1 could end up being closer to you than the issue is, so you get okay ping results but still unable to access resources on the other side of the issue
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.
The corollary is that when it fails, you've no idea what failed, or how it failed, or if the "fail" is even valid or relevant, because you're abusing a service that isn't designed for you and isn't fit for use. So if it succeeds, you really don't know, because perhaps your train's WiFi router is responding with a spoofed IPv4 address while it goes through the Chunnel. And if it fails, you really don't know, because you DGAF about learning formal troubleshooting methods and couldn't be arsed to find out your upstream router's address in order to simply isolate your PING to a singular link, rather than relying on complex routing rules, especially those introduced by "anycast". And perhaps you can manually dig in when your manual checks fail, but your AI agent or automated script DGAF about your nuanced knowledge that 1.1.1.1 isn't your upstream router; in fact it's not yours at all and has nothing to do with your network topology. But at least it looks elegant.