While i do agree with you, there might be a certain issue, at least with disc based media called disc rotting.Servers eventually go offline. Hard drives and memory cards wear down and break. Carts and optical discs generally only break if you abuse them.
Certainly at times digital sales are cheaper, but it comes at the cost of never being to trade them up for other games, or pawn a bad game off on an unsuspecting friend.
https://en.wikipedia.org/wiki/Disc_rot
Though in that type of situation it would probably take so long for something like that to happen that by the time it did, if it happens, it might be after any of our lifetimes.
