LinusTechTips, for example, already puts ads directly in the source video. And it's perfectly fine. What would being able to edit the video do?

Also, people already sell the rights to their viral videos.

Yeah, I mentioned that. And that sucks, because the viewcount of a video is one of the factors in deciding how often it'll show up in the Related Videos.

No, not and keep the same video ID. The trick is to create a one-video playlist, and link to the playlist. Then you can update the contents of the playlist whenever you want.

It affects the content creators that I like watching. It makes their job harder. It's easy to see how it affects them.

I pay for YouTube Red et al. so the content creators I watch get their fair share of my cash. If this begins to affect content, I'm going to stop subscribing to Red and stop watching YouTube videos altogether. It's a waste of time anyway and I have better things I should be doing.