That is simply ignorant.
Yes, because the opinions of people that actually own a product are worthless.
Depends on the product. User reviews are good for practical goods like ovens, vacumn cleaners etc.
Art, beer, RPGs are a lot more subjective.
A lot of people review adventures based on first impressions. These large books can't really be played through that fast so any reviews for say descent into Avernus for example are inherently suspect.
So a lot of reviews will be on impressions, how pretty it is or fun to read.
New player reviews are also suspect by new I mean played for 5 years or less. If they have only played 5E (and 4E) you missed a lot of the great adventures. You missed the Golden age of Paizo for example (say 2005-2011 or so). You missed Dungeon magazine.
Movie critic reviews for example are often useless as they tend to like Oscar bait type historical dramas.
Or beer review sites. They skew heavily towards craft beers so if one of them is a Macro brewery with reviews between 73-83% it's probably a very good beer at least for a mass produced one.
5E has a lot if new players, it's a good edition and yeah DMs can make ok/decent adventures a lot of fun. I would be highly suspect of any review if a new adventure that comes out less than 3-6 months of the release date.
Remember something like Out of the Abyss got great reviews but now people are saying it's a pain to run. Yet it still rates 80+% on Amazon. I would rate it 10% lower, doesn't mean it's bad still decent score but it has some big flaws.