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.
Some is not all. The was also the 3DO console, The Sega Saturn etc. If so many devs wanted to escape Nintendos grasp they had options even before Sony came along.
FF7 would of fitted since the was also the 64DD add on that was being released. Also look at Resident Evil 2 that game needed 2 discs on PS1.
Moneyhatting is how Sony got in this industry.