Yes, UV light appears less intense than blue or white to the human eye. But UV produces arguably more par (I've read people claim about the same par level as blues, some claim more, I guess it depends on the individual diodes being tested). The problem is when people see a UV diode that looks very dim so they turn it up full blast so it looks bright to us and bleach everything.
I don't know a whole lot about UV, so I'd take what I'm saying with a grain of salt.