... As a stand-alone means of load bearing though, there are serious limitations as to what can be carried comfortably inside a makeshift bedroll "pack". Certainly no larger, bulkier items such as pots, larger cooking utensils, water containers, food, etc. Also, a bedroll is not nearly as secure as a proper backpack. Easy to lose small items without noticing. And any time you need to get something from your pack, that will mean taking apart the entire bedroll, then carefully tucking it back together before setting off again.
This has been a fascinating discussion, so thank you all!
I haven't tried using just a bed roll, so I offer no personal experience, BUT.... from what I've seen and heard from friends and You Tube, it does seem possible that it's a practical alternative to modern backpack and sleeping bag.
Here's a video from my friend Karen showing her wool blanket roll - including water bottle, pot, cup, knife, saw, etc.... It's only a minimal kit for a day trip with her grandkids, but it looks like a pretty solid set-up to me. She has hers set up to be carried like a haversack, but I've seen other configurations as well.
Skip to 3:45 in the video to see the content of the roll:
https://www.youtube.com/watch?v=pX7ENQhao-oDave Canterbury, as you might expect, has used this method as well, and there are a BUNCH of videos on You Tube from him and others demonstrating it.