maybe it does, maybe it doesn't... early testing with UV on field crops showed no statistically discernable impact. Studies done on some indoor plants did show a statisticalyl significant impact, but hasn't been easily reproduced since then, so it's a little doubtful. I've heard of arecent study that showed it wasn't helpful. it's a complicated thing given the relativistic realtionships invovled in growing marijuana.
IR i've heard some are going away from it because it can cause too much stretch.
there's a lot of peple jumping the gun. "Belief" mostly depends on whether or not they've invested money into it, then instead of beinga rational decision it becomes more about ego and such things that are irrelevant.
The uv can have other postive effects not related to potency or yield. maybe it's real benefit will be something more preventatitve related to microbes and pests.
Anyone that gives a black and white answer on this doesn't understand how the scientific method works. early studies need to be verified. 90% are later proven to be false claims, so never invest too heavily into "initial studies show..." .. unless it is an incredibly easy question to answer - like, "is their a buildup of minerals in bud if you don't flush" .. and the answer is no.. not it does not build up, lol.. because this is a simple question with a simple answer given our technology available. either the molecules exist out of proportion or tey do not when analyzed.. they do not.