Why is it SOOOOO difficult to delete a podcast??

At best the delete option appears only in ONE menu option - but not always.

The "Delete from Library" option appears only once, where one would expect it: on the podcast page.

Then you can only delete one podcast at a time.

Wrong. You can delete any number of podcasts under Shows > Edit.

That is a lot of fun if the Podcast app decides to download EVERY EPISODE of a podcast.

You should distinguish "podcast" from "episode". To remove many episodes at once from the "My Episodes" list, simply change the settings for that podcast to keep less episodes. You might also want to check the general settings for the Podcasts app in iOS Settings. The choice whether to download every episode or not is not made by the app, it is made by you.