Can you raise a barbell or kettlebell off the floor to compensate for limited mobility while learning how to deadlift? Sure.
Should you stop there and not develop the mobility? I'd say no.
If we're talking training clients, there might be some who can't get there.
Should you be able to pick something off the ground? Yes. Folks like to complain about being too tall to squat, or apparently too tall to deadlift - but when you have to pick up a bag of dogfood or a child or a fallen tree branch, or maybe a box of books ... it doesn't really matter how tall you are. Things are on the floor, at various heights. The question is: Can you go? And if you can't - now what?
(Can you go / now what are taken from Dan John. Not original to me.)