Thank you turingtest2 for the explanation. Here's the thing, and Apple does this ALL THE TIME.
(I am mostly an Apple lover, but this stuff drives me crazy.)
They make something of a fundamental change to the UI, and expect that you will just "get it".
You make a casual comment about "That said, depending on the view, I think you should still be able to delete episodes that you no longer want to show in the feed." And you're right. But they change the view to be one that you didn't have before. And No obvious way to change it. If you don't believe me, look at all the threads under "delete podcast episode".
So of course, to change the view, one would click the menu option "View" and look at the options, yes? No! It's down at the bottom under "Show". Very poor UI design. And the intuitive choice (which I believe used to be the default) is now "Unplayed/My Episodes and Saved" (which is some kind of ***?, because even if an episode is played, it shows...)
Reminds me of when they arbitrarily decided to move the podcast refresh button, which looked very much like a browser refresh, and it disappeared from upper left corner, only to reappear as text in the lower left corner. I (like may others) was looking for the icon, not trying to "read" the screen. Took a while to find it. No huge deal, but WHY?
Anyway, through with the rant. My plea to Apple is to STOP arbitrarily changing the UI WITHOUT ANY EXPLANATION, and really, without any benefit, IMO. Thanks!