100 series fitment for snow chains

If you only have one set of snow chains, the general consensus of fitment to a 4WD is on the front – right? I agree with that, makes sense.

So why does the manual for my 100 series rigid axel say to only fit them on the rear?

I can only assume it’s because they either:

1) Rub on the guards.
or
2) With the increase in traction put to much load on the weaker front diff. I know it’s weak cause I’ve already had 2 replaced under warranty and not really put the car under excessive stress.

So, anyone know what is the real reason for the manuals recommendation, if it’s not one of the above?