It's incredibly fragile at the CDN level if deployed at scale for a start.
You'd see playback issues go up by 1000%.
In the nicest possible way, it is pretty clear that this article was written by somebody who has only ever looked at video distribution as a hobbyist and not deploying it at scale to paying customers who quite reasonably get very upset at things not working reliably.
What would be the problems? When I’ve looked into streaming video before (for normal, non ripping reasons), I’ve noticed that most are already playlists of segments. You’d just need to store the segments that are different between versions, which should be better than keeping full separate versions which is what they apparently do currently.