The premise of this post is wacky. They're trying to argue for how web applications should provide consistency to operations on remote systems. You know what that's called? Distributed Computing. I don't know if you know this, but Distributed Computing Is Hard. You can't solve it with a new interface or polling really fast.
Webhooks are perfectly fine for what they're intended, which is inconsistent push-based notifications to loosely coupled web apps. If you require "consistency", you supplement with polling and queues and other junk. If you require real consistency, you must use a distributed consensus algorithm.
distributed consensus/distributed computing appies for mutual/full-duplex/two-way systems, syncing changes one way from a 3rd party is not distributed computing, and not something you would want to throw a distributed consensus algorithm at
Webhooks are perfectly fine for what they're intended, which is inconsistent push-based notifications to loosely coupled web apps. If you require "consistency", you supplement with polling and queues and other junk. If you require real consistency, you must use a distributed consensus algorithm.