The D22 has less power. Its wheelbase is slightly shorter and it's narrower so it's less stable than the D40.
We weren't there to see it, we have one paragraph of text describing what happened. It didn't describe the ruts, the quality of the surface, how wet it was ...
If it was a 45 degree incline of wet red clay and the other cars chose to gun their engines to use momentum and the D40 tried to take it slowly it's obvious why there was a problem. A D22 doing the exact same thing would suffer the exact same fate.
The complaint here is how the front hubs wouldn't engage. Well, there's an interesting point here - the front hubs of the D40 don't EVER disengage. They're engaged full-time. The front diff is turned over by the wheels ALL the time. The thing that drives the front wheels - the transfer case - is the ONLY thing that disconnects the front axles.
So we're not talking about the hubs any more - they aren't an issue. The issue is in the transfer case. If you tried to engage 4WD and it didn't work, there's a problem in the transfer case itself. That's a fairly new vehicle and if there's a problem with the transfer case, take it back and get it fixed.
We've now had our D40 - not lifted or anything - through slick mud, sand, rocky tracks and a bonnet-deep water crossing. 4WD has engaged and disengaged exactly as expected - including the time when I intended to put it in 4LO and because I neglected to put the transmission into neutral, the car refused and I had to use much more throttle to get me through. After the crossing (axle-deep water + mud) I tried engaging it again, following procedure properly, and had no problems - it was just me not doing it right.