I've never used an RSS reader so correct me if I'm wrong, but RSS can basically allow you to read the content without advertising? Sharing is fine, but I think they would prefer sharing in a way that can make money.
I use RSS/Atom to keep up-to-date on the 100+ webcomics I read, and the content in those feeds can vary wildly. Some include the full comic page, some only a thumbnail, some contain an accompanying blog post, others are empty and you need to follow the link to see the post.
If you want to read everything in your feed reader, those "incomplete" feeds are disappointing, but I just use it as a kind of newsletter to get notified of updates. I even use Thunderbird's built-in feed support.
Most feeds only contain "excerpts" - which require you to visit the website to read the entire article. Thankfully, "reader mode" exists. Ads are also entirely possible, but not commonplace.
