Im not only talking about monster hunter world. If you honstly believe that Sony doesnt buy exclusives then im sorry but i cant be of help.
I guess all them devs in the PS1 days just wanted to trow themselfs at Sony....
Some of them did. Nintendo was known to crush independent developers when they were market leaders by limiting the number of cartridges that could be produced for third party games which also killed many developers.
Also games like Final Fantasy VII couldn't fit on a cartridge and needed the storage size of discs so they were made exclusively for PS1.
Moneyhatting wasn't always the only good reason for third parties to make exclusives.