The decision to move to PC is not "puzzling" if you have actually thought about what you gain. Except for collectors, the issue here isn't really about the discs at all.
PC is an open platform where multiple game vendors compete. GOG sells mostly DRM-free games with the option to download an offline installer, meaning that you can quite literally keep and play your games forever. Steam doesn't have that, but it does have a huge library of games going back a couple decades, almost every one of which is still available today.
Contrast that with all-digital PlayStation 6. This is a tiny walled garden. It will certainly not have meaningful backwards compatibility with any games before the PS4 era. It will also have no backwards compatibility with PS4 and PS5 disc games. It is a completely closed platform and a completely vertical distribution system in which the hardware vendor controls 100% of software availability and software pricing at all times.