I don't have access to your "many friends and acquaintances who are going bankrupt and shutting down fantastic independently run websites." I absolutely don't have access to the internals of their businesses to decide whether I agree that their problem is Google Search being hostile to independent sites. But I do have access to the traffic stats for the sites which I run.
Many of the sites with similar complaints seem to focus on product reviews and recommendations and have been hit by a specific Google policy which favors trusted and well-known domains for those types of search, even if that domain is not trusted for product reviews in particular. (So $glossyMagazineInNYC can open a line of product reviews and get lots of Google traffic, while $smallProductReviewBusiness loses traffic).
Many of the sites with similar complaints seem to focus on product reviews and recommendations and have been hit by a specific Google policy which favors trusted and well-known domains for those types of search, even if that domain is not trusted for product reviews in particular. (So $glossyMagazineInNYC can open a line of product reviews and get lots of Google traffic, while $smallProductReviewBusiness loses traffic).