1st party games are what helps define and choose one console over the other seeing as most 3rd party games are now multiplatform and exclusive 3rd party games are more of a rarity.
Sidenote: The worst thing about a 3rd party exclusive is the annoying people that keep whining and demanding that the game goes on other consoles lol
TBF, third party exclusives aren't dead. They just evolved with the times. So now you mostly have timed exclusives and console exclusives which are ported to other platforms after at least a year.