Don't you think if they're paying for reviews, they'd want a slightly better review description than 'Good' or 'reviewer'?!
Yes, but that would cost a
lot more and the main point is the rating because that's the first thing anyone looks at, the only thing most people look at and the thing that's used in advertising. "We have over x thousand 5* reviews!"
It makes more sense because it gives better ROI. It's more effective to spend money buying 10,000 fake 5* ratings with one word "reviews" than spending the same amount of money buying 1,000 fake 5* ratings with anything more than one word for the "review". Ethical considerations are irrelevant once the company has decided to buy fake reviews, so the only considerations are ROI, the chance of getting caught and the costs of getting caught. It's so normal that the costs of getting caught are usually zero, so the chance of getting caught doesn't matter. So it's all about how much fraud you can buy for a given amount of money and that's almost entirely about ratings rather than reviews.
I try to work around the fraud by first reading the lowest rated reviews and trying to judge how reasonable they are, but it's hard to get a genuine picture because ratings are given such high priority and fraud in ratings is so widespread.