I'll steelman the opposite side; YouTube creators have no rights.
When you upload a video to YouTube, you are licensing Google to redistribute a copy of your content at their whims. The uploader agrees to give Google "a worldwide, non-exclusive, royalty-free, sublicensable and transferable license to use, reproduce, distribute, prepare derivative works of, display, and perform" your video.
The video you upload to YouTube isn't yours anymore. You can pretend it is, and play around with it like a little paper doll for all it's worth. You don't own it anymore though, and your right to judge where it is and belongs is stripped the moment you click "Upload".
To the extent taking notes on a video without permission is a thing?
The outcome is not competing with the source video. Anyone's who's interested in the topic would likely still choose which video they want to delve into further.
YouTube channels routinely analyze each other for content and doing it as well “in their own way”
Packaging content in a different way is similar to repurposing content for different social media platforms.
Heck some people share other peoples content on different platforms.
This site is putting a particular lens on a video and sharing the perspective it generates for those who like it.
If it became a product for video creators to generate content for a better description they might never need the site.