Online ratings help people make choices, but the people who leave reviews are not always representative of everyone who used a service.
Reviews are useful because they give us some information before we spend money or time. They are also a strange sample. People with unusually good or bad experiences may be more motivated to write, businesses may ask selectively, and fake reviews can distort the picture.
A score compresses many different experiences into one number. I try to treat it as a clue rather than a verdict, and to look for details that explain what a reviewer actually valued. The rating can narrow the options, but it cannot remove the uncertainty from choosing a restaurant, hotel, or product.