Video content could be in itself another argument in favor of GP's thesis. There seems to be dearth of high quality video material. You have big-budget high quality videos, big-budget garbage, and then lots and lots of low-budget garbage: i.e. all the stuff "influencers" and "YouTube personas" create to live off ad revenue.

There is a small and somewhat obscure but relatively stable middle - low-budget, high-quality videos. I attribute its survival to two things: some live off Patreon donations and occasional sponsorship deals, others live because the creators have an actual dayjob, and they do YouTube as a hobby. This is similar to blogs - best ones are done on the side, with no expectation of revenue.

I see more of your latter paragraph. In several of my interest areas there is a good amount of useful content in videos. Best example is probably electronics, where a lot of tribal knowledge is now more accessible than ever before. Practical mechanics, both old fashioned (metal and woodworking) and new (CAD design, 3d-printing), also has a lot of useful video content. While there is a lot of pop-commercial "personas" making noise with their videos also, it does not seem to have hurt output by "in it for the passion" people.