it's the list of feeds that is hosted by apple (think of it as a search engine for podcasts), not the actual feeds or media files.
Your question is the same as: "Why do you care if $YOUR_SEARCH_ENGINE (google, kaggle, duckduckgo) hosts a list of websites?"
The last search engine to host a list of websites was Yahoo!, and nobody did care.
The UX on the latter side is clearly superior.
in the past i've subscribed to a dead feed this way i think because the author changed who they syndicate through. i assume Apple's directory is maintained in a way that largely avoids this (simply by it being the canonical directory).
You could, but I suspect most people search in their podcast app. Which is where apples directory comes in.