I would say within a niche on something like youtube you will find the content is different from other topics but the format and "what works" is all the same. In-spot ads are the same companies pushing the same stuff - ray con, hello fresh, if its gaming its something shadow legends, etc. Do these channel owners actually use that stuff? (rhetorical question)

Any new person into a space has to mimic others that are successful in order to get views - copying thumbnail formats, topics, video length, "putting links in the description in case you're interested" (aka buy stuff with my affiliate code), etc.

This leads to content within a niche forming a monolithic format/topics because they are all following the same "what works" roadmap for every channel in that niche. Everything is for profit, to do things counter to that means it is unseen, except rare cases like LockPickingLawyer but even his stuff is now pushing the products they make.