iPhones have only just gotten support for acting as Bluetooth authenticators, and from what I can tell, Android devices have only had it for a year or so. So we only now seem to be at the point where most people would have a device they could use as a WebAuthn authenticator across multiple devices, making it only now a viable replacement for TOTP for most people (without buying a hardware authenticator). I don't see anything shameful about still supporting what was until recently the best option for most people.
(Personally, I'll be waiting until 1Password gets WebAuthn support before moving to it from TOTP.)