Branding depends on a reputation. That reputation needs to be established by either word of mouth or general reviews. For mattresses, word of mouth isn't that

Branding depends on a reputation. That reputation needs to be established by either word of mouth or general reviews. For mattresses, word of mouth isn't that good because people have different preferences. Moreover, general reviews have essentially been corrupted by 'astroturfing' reviews. That is, almost all mattress reviews that are prominent are financed by a manufacturer. They then use publishing clout or heavy SEO to be found over any possible remaining reviews. Besides, single user reviews aren't that valuable because of personal preference and lack of comparison mattresses. Thus, it is really hard for an honest reviewer to start. They need capital to get sufficiently many mattresses. Then, they need to be found, thus going up against the heavily SEO'd dishonest sites. Finally, they need to stand up to all attempts from the mattress companies and dishonest reviewers to actually survive. Finally, bad-mouthing brands' product quality is again stymied by personal preference and the small number of mattresses anyone sleeps on.