Jacking Points on a 2006 Mustang

I was reading in the owner's manual that FoMoCo says to not jack up the rear of the car using the rear axle diff. housing. Is it because the rear axle housing isn't strong enough or is it purely a safety thing? Also, are there other jacking points besides the 4 shown in the owner's manual?

Thanks

(Apologies to all if this belongs in the V6 tech section - is so, could a mod move it there for me, please?)