[pinum]

Creators are strongly disincentivised from doing that since deleting the old version would throw away their views etc for that video. It would also delete comments, and while this is often no great loss, I do run across useful or interesting YouTube comments sometimes.

[jakobegger]

They don't need to delete the old version, they can link between new/old version in the description.

[tastroder]

That sounds like a solution I'd personally never even notice. Most of the devices I consume youtube videos on either do not show the video description at all (TV) or actively disencourage reading it (the official Android app currently requires one or two clicks to even see it).

In addition to that, re-uploads are annoying enough as is because content creators constantly need to upload old content due to changes in Youtubes policies or enforcement. New revisions for any minor mistake instead of an overlay would properly ruin the subscription page imho.

[solarkraft]

This still fragments your audience.

[anjc]

This would be far more confusing than an annotation.