The trouble with using text as a branding tool on web pages is that it gets in the way of what visitors are looking for. Visitors want and expect text to be useful and information. They are in 'active' and 'engaged' mode. They are searching. They want something. Text that isn't useful is disappointing.
My worst experiences with hospitality sites have been to do with vague location, online timetables, poor follow-up communication, and out of date information. I have wasted days as a result, which I hate.
I think that the people who give the testimonials do so for the additional exposure they receive for their own names, sites and businesses. I also think they do some mutual back-scratching, and hype each other's products and services. In other words, the testimonials are just additional sales text. They have no credibility as outside, third-party endorsements.
The key to a successful advertising campaign is repetition. The same is true for a successful Web site. Marketing managers know that repeat contact with prospects develops an affinity for your products and services - and therefore, greater revenue.