Most times, reviews from the public domain as such holds no water but in a community like bitcointalk forum where people of like minds exist can be guaranteed when the trust is gained, and before that happens, you are sure you merited the trust and reviews from a genuine source who has used your services on the platform and they can confidently vouch for you without any fear or favour from anybody not public where reviews can be easily paid for tricking the masses to believe what isn't genuine.
True, but a stranger can't exactly be recommending services to you, for this to happen the person recommending the service to you has to be someone you trust, and the person must have had first hand experience with the company in question or knows someone who has and of course forums like this one help to as you even get access to a wider array of potentially satisfied customers who may have required their services in the past and can recommend them to others, this way the can reach a wider audience and market their services to so many other people who might be in need of it