Have you heard of Local CDN? It provides at least some common things.

What I meant were CDNs such as Google’s providing common resources like fonts or JS libraries.

There’s a difference: Websites have JS and requests to CDNs. RSS feeds don’t.

I do remember a Moderator from the subreddit saying exactly that. Apparently “a certain” ROM’s community was very vocal about their preference and provoked heated debates to a point where it was too much effort to moderate manually.