I watch a lot of videos related to two of my hobbies fly fishing/tying and ham radio. There is very little in the way of sponsorship or paid reviews and nearly all videos on these subjects feel rewarding to watch.
Technical content on the other hand is a whole different ball game. If I have to learn a new framework or library I used to head to YouTube first to view a few tutorials before diving in to the docs. The quality of these has declined because a lot of channels are just churning out tutorials without really understanding the subject matter. In some cases they are just video versions of the getting started tutorials on the libraries website. There are loads of channels where they churn out new low quality tutorials every day on a wide range of subjects - jack of all trades, master of none - but they are doing something right because YouTube places them high in the search results.
And as for the bigger channels on popular subjects such a gadgets, computers, food and gaming - yes I do feel like they are often feel like the content support the advertising as oppose the adverts supporting the content.
I think to get value from YouTube you just need to be a bit more choosy. There is still good organic content being made, but it sits behind all the stuff that is primarily designed to get high up in the search results and make money. Remember, the way YouTube ranks search results and places suggestions is designed to benefit them more than you.