I wrote it above, but will write it again. It’s not for navigation, but for orientation on electronic maps/charts that are becoming more and more common with portable EFB computers such as iPads etc.
Most companies issue those to pilots, even if the airplane itself has an $1million built in EFB (which is cr@p BTW).
Having a GPS, which displays ownship position is not crucial, but still a‘nice to have’ feature, enabling better orientation on the map and doing eg. electronic plotting on oceanic flights.
My airline is now in the process of enabling the GPS on our EFB tablets, even though the airplane itself has an impressive combo of NAV sensors, including a dual GPS receiver.