You can see a comparison of the different indexes (indices?) at https://podcastindustryinsights.com/
Full disclosure, I work for a company that provides a paywall to podcasters. (Among other things.)
Maybe I wasn't able to scan the Terms of Service well enough, since I didn't see it defined there? They mention they can remove content there, but not why they would.
I think the move to announced seasons is a good middle ground. It tempers expectations and gives creators a break or stopping point.
It's simply that the podcaster provides something valuable to you with their podcast and you're expected to return an equal amount of value back to them in whatever form you choose. It could be a Paypal payment, cool artwork for the show, topic research for the show, or whatever value you can contribute back.
Check out value4value.info for a more detailed explanation
I tried to build a better way to see what my friends are listening to with https://lastcast.fm, but I've since shut down the project.
But its less about discovery than tracking your library and playing them back.