He misses another benefit of writing reviews: rewarding good businesses. And even, in the case of a thoughtful review, enabling a diversity of services -- simple star reviews can't express the give and take of different kinds of service, and so a decrepit-but-lovable hotel can't be distinguished from a decrepit-and-neglected hotel. Reviews make it possible for people to find the right hotel (or any other service) for their wishes, and they don't have to rely on crude measures like brand loyalty.

I honestly can't decide what the personal benefit is. If reviews can make a difference in a business, then one review can make a difference -- unlike "likes" or votes or stars a review is not automatically aggregated, it is specifically read by other people. So there is real potential that a review can positively impact a business you like, and provide you real benefit as a result. The negative impact of a bad review has no direct benefit that I can think of -- you will never return, and the only happiness you might derive is schadenfreude if the business's fortunes decline. Either way though there is a sense of satisfaction, which seems to be the primary reason people submit reviews.