I'm referring to Honda and it's seemingly having no idea.

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Well, from Honda's response the rears do engage in normal conditions but not if they'd be sent all the power as the rear diff can't deal with the full output of the engine.

 

While I can imagine a situation in which three wheels have zero grip and the car has no momentum, it sounds pretty unlikely, so whether this behaviour translates into a real-world limitation I am not sure. Particularly with winter tyres, which ought to prevent any wheel being utterly devoid of traction in almost any situation.

The Haldex system can't send 100% drive to the rear either, but it would cope with that (admittedly false) situation (two wheels on rollers I mean). That said, you don't need 100% drive to the rear to get out of this... any drive to the rear will help if the rears have some traction; the fronts will just spin a little (or not, if controlled by the traction control) until they get traction themselves.

I think Honda's explanation is a little bit grasping at straws. If all other temporary 4WD drive systems can handle it, why can't theirs? That said, Honda have some heritage in engineering, so maybe they know something we don't.

Just read the original source for this video clip at http://teknikensvarld.se/honda-cr-v-4wd-system-is-not-working-again-163708/ and thought the comments were instructive:

1 - Honda "fixed" the 2013 model with a software update (hardware in some cases) - users reported the change worked.

2 - Teknikensvarld retested a "2014 model" and found the poor performance recurred, blamed Honda.

3 - Observers commented though that the model tested was actually an older build (by its VIN number) and likely had not had the software updated...

4 - No comment from Teknikensvarld or Honda PR on point 3 though.

 

PS: The next 2015 CR-V 1.6 4x4 might be interesting competition.