Imagine two plumbing businesses appear in someone's Google search results.
One has 12 reviews. The other has 180.
Both might provide excellent service, but the business with more reviews gives potential customers more feedback to consider.
People can read about previous jobs, customer service, reliability and the overall experience. That doesn't mean the business with the most reviews will always get the job.
Price, availability, location and other factors still matter. But reviews can help someone feel more comfortable making an enquiry.
This is particularly important for trades and home services, where customers may be inviting someone into their property or paying for work they don't know how to assess themselves.