Manufacturers have 100% control over their website. They can delete reviews, they can keep the reviews and start shipping a slightly different product instead,

Manufacturers have 100% control over their website. They can delete reviews, they can keep the reviews and start shipping a slightly different product instead, they can ask certain customers to write positive reviews for incentives. The list goes on and on. It's asymmetric warfare and manufacturers hold all the cards. That's why there generally are consumer protection laws, and not the other way around, e.g. protecting manufacturers from consumers (lol). The semi-good news is that for most consumer goods like microwaves, it doesn't really matter, because they are all "good enough".