[Neil Jones]

Freevee is the old IMDb TV which Amazon have chucked a lot of money at for content, particularly after they rebranded it. (namely Judge Judy's knock off of her old show in new colours, and the revival of Neighbours).

I believe Prime Video is also supported by more devices than Freevee as well, which may have been part of the reason why they may be taking this course of action.

Even on the Amazon Firestick Freevee effectively redirects to the Prime app as a separate entity or category in that app.
can't comment on other devices but I wouldn't be surprised if other platforms are the same.