Comment by PaulHoule

That blogger talks about his speculations which I agree with.

Google has been fighting against SEO spammers since the very beginning, in fact there was keyword stuffing even before there was Google.

Google at some point made a decision to privilege sites like Forbes because they were dealing with hundreds of subprime sites that looked even sketchier. Rather than playing whac-a-mole with new spammers every month as they change the rules they could put sites like Forbes and Wirecutter on top, ultimately discouraging other SEO spammers from even trying, and being able to manage the relationship. (e.g. if you see Forbes rank for "best CBD gummies" just once it looks a little sketchy but you get over it, you only really catch the bad smell after you've done 5,000 searches and see Forbes ranks so high on so many of them)

I've been working with a financial analyst to quantify the value of online engagement (what value does YC get from an HN comment? what value do users get from it?) and reviews are one of the clearest examples since a review adds or subtracts revenue from a vendor and gives customers a certain amount of satisfaction. It's an interesting area in my mind because the stakes are so high.