Why one platform is not enough on your own site
Your Google rating is what search shows. Your website is where someone decides. Those are different moments, and the second one is helped by breadth — a visitor who sees reviews from three sources reads it as harder to fake than the same number of reviews from one.
One widget takes all seven, with source tabs if you want visitors to filter. Reviews arrive together and stay current without anyone copying anything.
What to do about the ones you are not on
Start with Google and stop there until it is working. A business with forty recent Google reviews and nothing else is in a stronger position than one with eight reviews spread across five platforms, because eight-review profiles read as neglect.
Add a second platform when the first is healthy and there is a reason — an audience that lives there, or a buyer who checks it. Collecting reviews is the same effort per platform; the question is which one repays it.
Industry pages for local trades
If you are in a specific trade, the industry pages come pre-configured with the sources that matter for it: local services, restaurants, beauty and salons, dentists, home services and law firms.