I just moved into a new house, and it has a weird step in the bottom of the closet, that is covered in carpet. I’ve seen this before, and it could just be coincidence, but is there possibly a weird architecture or design reason for this, or is it just a quirk?
It’s almost certainly hiding vents or pipes that needed to be routed there. As for the carpeting, somebody no doubt thought it would be cool, or else if for sound dampening.