Yes, not saying that web of trust ever worked. "Pre-established channel" are the other mechanisms I mentioned, like a central authority (https) or TOFU (just trust the first key you get). All of these have some issues, that any alternative must also solve for.

So if we need a pre-established channel anyways, why would people recommending a replacement for GPG workflows need to solve for secure key distribution?

This is a bit like looking at electric cars and saying ~"well you can't claim to be a viable replacement for gas cars until you can solve flight"