In message

, at 03:39:08 on Mon, 27 Oct 2014, Recliner
remarked:
Not permanently locked ones, but a brake in the diff (rather that at the wheel).

What would be gained by duplicating the function?

Braking a wheel isn't the same as locking a diff. Apart from anything
else, the locked diff still powers both wheels.

No it's not the same, but it's what traction control is. And ASC can still
power both wheels, independently reducing torque on each wheel to the level
that the tyre's grip can sustain. That provides more traction than a simple
locked diff.

A locked diff is providing traction via the non-slipping wheel, except
the "slipping" one isn't - because it's rotating at the same speed as
the "non-slipping" one - and is therefore well placed to start providing
traction as soon as road adhesion returns to that side.
--
Roland Perry