I can't play slap. I'd like to be able to but have never managed to get my fingers to co-operate, and can't see a real use for it in any band situation I'm ever likely to be in. I'm not averse to others using it and it's not mandatory for me to watch any Youtube videos with it on. If thine Youtube offends thee, turn it off. However, if someone intends to demonstrate the capabilities of a bass and does nothing but slap on it, that's not a good demonstration.
I thought that slap interplay between the two street bassists was rather good. Couldn't have coped with two 45 minute sets of it though.
And a while ago, in a prog rock covers band that never fled the nest, we did a couple of King Crimson numbers, Epitaph and Court of the Crimson King. For one of them, there's a video somewhere on Youtube with a post-Greg Lake incarnation of KC performing it, in which the bassist at one point plays some slap and demonstrates why you should never play slap in prog rock.