I think you’re thinking of declawing.
Trimming nails is good for the cat because otherwise the nail grows so long that it loops around and stabs into their hand. In the wild this is fixed by them breaking off as they do normal activities but they don’t do that nearly as much in a domestic situation.
Declawing though, is cruel
Nobody is talking about cutting the whole nail off… We’ve been saying trimming this whole time. I don’t know where you got the idea that we were advocating cutting blood vessels instead of just doing the safe bit.