Does chronic stretching lead to longer limbs?
Never heard of this concept. Stretching might help limbs appear to be longer by enhancing some supporting muscle groups and firming them and toning them, but in all my reading on health/fitness and such, I’ve never heard of such a thing.
Ask Bobby Brady…
he’s still hanging in the closet. 
Nope. Longer limbs would require longer bones, and bones are unaffected by stretching.