Do you just mean because any physically realizable computer is a finite state machine? Or...?
I wouldn't describe a computer's usual behavior as having constant depth.
It is fairly typical to talk about problems in P as being feasible (though when the constant factors are too big, this isn't strictly true of course).
Just because for unreasonably large inputs, my computer can't run a particular program and produce the correct answer for that input, due to my computer running out of memory, we don't generally say that my computer is fundamentally incapable of executing that algorithm.
I wouldn't describe a computer's usual behavior as having constant depth.
It is fairly typical to talk about problems in P as being feasible (though when the constant factors are too big, this isn't strictly true of course).
Just because for unreasonably large inputs, my computer can't run a particular program and produce the correct answer for that input, due to my computer running out of memory, we don't generally say that my computer is fundamentally incapable of executing that algorithm.