I don't think "zero editorial oversight in between the author drafting the post and it appearing on Forbes' website" is equivalent to "mainly a blogging/self-publishing tool like Medium", given the large amount of editorial oversight evidently involved at other stages of the process. And, though I agree that Forbes's cachet is more of a motivation than contributor fees, "The author, Brad Templeton, is not employed or paid by Forbes" is evidently a flat-out lie.
Based on what I knew from about five years ago, "it's complicated."
At least at the time, brands could buy a slot. I wrote for a company a couple of times. I think the pieces were very lightly edited.
There were/are also "contributors" who were mostly individuals who didn't have gross obvious conflicts of interest in the topics they wrote about. I think they either wrote for free or were paid some nominal sum. Again, I think there was light editing.
The latter is also what you saw with the CNET Blog Network which I did write for over a number of years at a time when everyone was branding and blogging including journalists and analysts. (I declined to accept money for various reasons. Other people were paid a modest amount.)
The problem with these things is that there are always going to be conflicts of interest and biases to various degrees. Some organizations try very hard to weed out direct examples of the former at least outside of explicit op-ed pages. But it's hard to manage. To give a current example, maybe you're bullish on generative AI because you work or consult for a company doing it no matter what reservations you have. Or maybe you work for the company because you're bullish on it. Or back in the day Microsoft's a client of your's because you really like what they're doing and they engaged you and passed on the Unix expert who didn't think much of what Microsoft was doing.
CNET got increasingly uncomfortable with the whole model and dropped it.
