There are ways around this. I use ttrss and it has the option to fetch the actual page and replace the RSS content with it. It has a few bugs with formatting and such on some sites, but generally works well. There is a built in Readability plugin for it, but I also use a plugin called Mercury full text for some feeds that don't play nicely with Readability.

Mercury works better than Readability usually, but the downside is that Mercury uses a third party to process it, whereas Readability is all local. So some sites will block Mercury from accessing it, because it's seen as a bot (Forbes does this, as do a few other sites).

This combo works great for reading entirely in your RSS reader. I use my phone to download my feeds for offline before flights, so I can read the actual content as well without an Internet connection (assuming it doesn't have formatting errors).