If I bought everything digitally, it could all be lost if that one SD card or hard drive died. And getting them back via receipt is only possible so long as the provider doesn't go out of business or decide they just don't want to provide them any more.
Plus, if I bought everything digitally, I'd quickly run out of space and have to spend more money to buy another SD card or hard drive.
The counter argument is that physical also has issues depending on the format as discs do wear out over time while solid state formats also share the same risk of dying like hard drives, providers going out of business or not providing the product anymore hits both digital and physical only with digital depending on the platform the game can remain available for purchase if they go out of business or still be redownloaded if the publisher pulls the game because of consumer rights laws an example are the Crysis games on Steam I can still download them on Steam even though EA pulled them from Steam long ago. With physical if something happens to your copy you could end up having to pay hiked up prices to rebuy the game.