I actually prefer this approach. Basically go around websites not serving full articles via RSS by parsing them via Readability or mercury-parser or whatever.
Can't back it up, but I'm pretty sure some online RSS services use the same trick. Makes for a better UX than "click here to read the full story".
So critical. So some parsing is done off the device due to performance constraints. You'll need internet access anyway to pull down the RSS feeds, and a middleman Lambda/CF worker won't add much latency. I think it's a perfectly acceptable tradeoff.
So not really an RSS reader.