I think you mean Podcast Addict?
They have resources (money and dev time) to burn that they were willing to put to the issue so they could capture hosts like Anchor that only support WebSub.
The other technical problem is reliability. 90% of the universe uses the free Google websub hub. And it absolutely does not send notifications all the time reliably. So you still have to poll.
I wrote more here (under the WebSub heading): https://podcasting20.substack.com/p/podping