No doubt they can be useful in certain conditions, but they are NOT required to keep a clear, algae free tank with healthy fish.
Regular water changes, sensible stocking of the tank, sufficient mechanical filtration, balanced plant nutrition, etc etc can get you there without sterilizing.
Likewise, a UV sterilizer will not be the cure for all algae.
Just wanted to make sure nobody gets the wrong ideas. It's a "nice to have".