I am genuinely curious if anybody knows of a non-trivial problem being solved on one of these forums, at least for a huge company that’s palming off customer support. It just feels like screaming in to the void, only for someone to (deliberately?) misinterpret your question and give you some generic advice.

Every suggestion when encountering a Windows OS bug is "run sfc /scannow" - has this ever solved a problem for anyone?

It depends on what you call "non-trivial". I found answers on how to circumvent dumb macos bugs on Apple forums at least twice in the last 6 months. One related to displays, I was about to return a new USB-C monitor which wouldn't turn on. A silly issue, but it's a bug on my book, I wouldn't find the answer on the docs.