[rambambram]

> But using rss means most blogs will already have compatibility with you ready to go so it’s a huge get for lowering the barrier of entry to your service.

This is a very important characteristic, making it possible for any new software to immediately deal with real content. Without paying a cent for that content.

Besides, the OP might conflate a thing or two, just like you point out. RSS is an open protocol, not a closed source app with guarded walls (there's not even a garden behind these walls anymore). RSS is so simple and open, one might even type their XML feed by hand.