Money is definitely a big factor--but if we look to 2022; there was a surpsisingly little amount of merchandise for The Weeknd (Atleast, at the start I think). Alongside that--The Weeknd was omitted from the collage merchandise (even though he was front and center for promotional).
Think there is more creatively at play, but that's just from the observations I've seen. Money matters; but I think Abel's love for Horror (and HHN as large) may be a predominant factor to more intently wonder on. If The Weeknd is back, I wonder how extensive the collaboration would be this time around--if Mike Dean would be involved again with the remixes and what-not.