Persona Collection Bundle Released on PS4, PS5, Xbox, Nintendo Switch, and Steam

It's worse than that, you can't even get it for yourself at all if you already own anything in there. Or at least I don't seem able to do anything but get it as a gift.
Apparently the publisher can either set it up like that or have the usual partial discount you mentioned, and Atlus unsurprisingly chose the most infuriating option.

Sounds like business as usual for Atlus