It is critical to get good lube on the splines, the stock stuff doesn't cut it.
A few years ago the stuff sold by Renault dealers for the CV joints on their FWD cars was the best around, and it was the only thing which would stop the splines on a Triumph IRS from locking up, and locking the suspension.
I still had half a tube left and use it on the BMW splines, it improves suspension action too, so it must work.
If the same thing happens on the BMW drive shaft and the splines lock up it will try to pull the shaft apart, and the circlip at the cush joint is the weakest point.
So good lube is essential.
I wouldn't pay too much attention to the yank assholes on ADV - I doubt if many even own a bike - they just trawl the net looking for a chance to vent their potty mouth and look clever, but ask a question which needs a bit knowledge and you wont get a sensible answer, other than parroting out something they have read somewhere, and usually dont understand.