On my phone it lets me download Apple TV+ content. The files are shockingly large compared to what Amazon Video downloads are. A 1 hr clip was maybe 800mb in prime, but a few gigabytes from apple. (I don’t have any on my phone atm, but a quick search is telling me episodes of “For all mankind” are ~4GB and an hour long) It looks noticeably better, a massive step up that is completely worth the extra bytes.
On my desktop I always rent stuff through iTunes just cause I can download it in advance, and don’t have to deal with buffering or reduced quality.