I take the points.
We briefed our wedding photographer to do just that, walk about, behind the scenes get more 'reportagey' stuff. But I'd still argue that the limited shots I saw of this work went way-way further than that. Just when normal people say 'reportage' they probably mean 'not posed' rather than 'capture the chaos behind the scenes'.
FWIW, I've never seen any work - FB or otherwise - from any of the weddings I've been to that are as candid as the ones in the link. Not saying it doesn't happen, it's just maybe when people say that, they don't really mean it.
But, as you say, I don't know what I'm talking about from a photographer's POV.
And, by the way, I don't agree that wedding photography is the lowest form of whatever he said.
I know there was no one working harder on our wedding day than our photographer. Especially as it was pre-digital, and he had a book full of prints ready for the evening reception.