They do, but it's irrelevant to performance nowadays since you're required to install all of the disc data to the SSD before you can play. The PS3/360 generation was the last time you could play games directly from a disc (and even then some games had an install process).

I believe even then it was already "most", at least for the PS3; that was the era where always-online devices became the norm, where game developers were more eager to release patches after release, etc.