My feeling is that reviews of anything need to be honest, and have enough balance people can pick and choose what they think is vital. A pro or con list must be accurate to be of any use, or perfectly good items get rejected and potentially bad ones get purchased. I have no problem with testing something and telling people what I found - but I have trouble in assessing validity from strangers. On this forum, for example - we know people's likes and dislikes after a year or two and we know their little picky areas - so when lazer, for example says the distortion wasn't really enough - I know his liking for it - so his comments make sense in context - because he pays lots of attention to that area. Still useful comments, and people can ask questions on a comment "was that when you had the XYZ in or out?" and he can say absolutely IN. The danger with unattributed comments is that the statement of crapacity could have been made by a person eminently capable of proving it, or by a 14 year old using a cheap laptop and pirated software on earbuds who knows little. In the middle come students with the often totally misunderstood process they got wrong and slagged the product off. Collecting negative reviews on hotels for instance, shows trends maybe - but often the review of a place you stayed in happily makes you wonder?
Like trustpilot - if you don't swear and curse, your review could influence people the wrong way? Worse nowadays, false claims that damage reputation can cost you! I don't like XYZ is honest opinion. XYZ mislead in their specs and employ child labour might be actionable.