Earlier quoted context omitted.
If you right click a link and open in new window (or middle click), the frameset was gone and only the piece in the frame was visible. Also you could not bookmark anything. I remember doing a frameset per content frame url automatically and also redirecting to that frameset from inside the page via javascript if the content frame's url was directly opened.
Framesets were great. >If you right click a link and open in new window (or middle click), the frameset was gone and only the piece in the frame was visible. Feature, not bug in my book. Same thing happens in today's iframes. But for situations where that is a problem, the spec could have been extended to support every page being able to identify a preferred parent frame. Or browsers could have changed behavior to by…
For multipart frame targets, the fix then, as it is now, is to parse out the URL fragment params into something reasonable. SPAs use the path for state; no reason you couldn’t use it for frames.