My take on this is no they don’t. As long as they are truthful they only report on the quality of the product and prevent many people of spending a lot of money from losing it by buying something that doesn’t work.
If your product is shit your company does not deserve to be shielded from the backlash, this is the core of (classic) capitalism after all.
5 star reviews are mostly worthless, they have a strong likelihood of being fake, or for people who only ever post 5 or 1 star reviews. A product with fewer 5 star than 3 star reviews will likely make me shy away, if for no other reason than the dissenters are drowning out whoever the vendor hired to fake reviews for them. That’s noteworthy.
4 star reviews are more worth reading. There is a set of folks who thinks 5 stars should be reserved for extremely good exceeded expectations, and merely “as expected” should not get top marks. These are more likely written by people who bought the product and care about what they’re talking about.
3 star reviews will have actual good consumer information in them. “I was looking for a box to hold my Shark Model no. 24352097ASDF0872RSD vacuum cleaner accessories in, and this box does okay but the wide brush attachment thing doesn’t fit anywhere.” Okay, if I have that model of Shark, I know this might not be the box to buy for my vacuum accessories. It’s not that the box is a bad box, it’s just this isn’t the correct use case. Thanks fellow citizen!
2 star reviews are almost never written because you seldom dissatisfy a customer below the middle of the scale without completely pissing them off.
1 star reviews come in a wondrous variety. Anything from “product never arrived” which you’re warned is wrong to leave in the product review because so many of these platforms are designed to separate the product, seller and delivery service for maximum customer violation, but okay. You’ll get “Product wasn’t as advertised at all, ordered a coffee grinder got a salad shooter” which can sometimes happen when dropshippers misuse the listing sub-options menus. You know how if you order a T-shirt from Amazon you get one listing on which you select size and color from drop down menus? Or Duct tape: 1 pack, 2 pack, 5 pack? I’ve seen sellers who probably don’t speak English as a primary language market completely different products like this, which leads to dumb shit like reviews for several different items mixed together. If I see a lot of 1 star reviews, and many of them are “soldering iron did a terrible job curling my hair” I take that as a good sign, because the seller feels legitimate enough to let those remain up. Illegitimate sellers can’t tolerate low review scores and will try to have them removed or hidden. Or, you see a pattern of “flashlight power button quit working after 3 months” in which case you know to legitimately avoid this flashlight because it legitimately isn’t well made.