Reviewers aren't (or really shouldn't be) beholden to companies, the whole point of a review is to give an opinion on a product, and the less input into that the company has the happier I will be. At the same time, some reviewers do hold a lot of sway, and can strongly influence people's opinions with their reviews, so there might be an argument that a negative review can impact sales. However, so what? If the reviewer is bringing up their concerns or issues with a product, that is the whole point of what they do, and their viewers will want to hear about those things (working on the assumption that people will tend to watch reviewers they think align with their own views), and would be pretty upset if they weren't warned about the downsides prior to purchasing.