Why is Combat Paralysis a physical (HT check) Disadvantage?

[Anthony]

Originally Posted by Bruno

My vague guess is that in 3e it was aimed at animals with a "freeze" reflex

Most such animals have IQ 4 or lower, and simply not giving them combat reflexes accomplishes freezing very effectively. I think it was aimed at PCs with high IQ and low HT.

Originally Posted by Bruno

And then it just sort of got copy-pasted into 4e.

This, however, is very likely.