Why weren't they going after this 10 years ago? I think I've just gotten into the habit of "open in new tab" because I know there's a good chance "back" won't do what I want.

Frankly, here on PieFed, "back" to a feed isn't very useful, because you'll just land somewhere in the feed, not back to the place where you started. "Open in new tab" solves that as well, for certain very small values of "solves."