It is when the main competition forces them to use DRM. The fact that the Xbox One has mandatory DRM changes things for everybody, including Sony.
That the XBO has an inherent, systemic DRM that prevents resale does not lead to conclusion that the PS4 has an inherent, systemic DRM.
Under Microsoft's system, while they try to foist any responsibility onto the publishers, it is at a basic system level that used games, lending and gifting are inhibited - due to a tying of physically purchased games to an account/console. Publishers are not opting into blocking used, they are simply given the option of opting out of blocking used; and aren't even given the option of opting out of 24-hour check-ins.
If Sony simply do not tie physically purchased game discs to an account/console then that in itself allows the above, and they can still let publishers do as they wish, subsequently, but at their own risk. They could in theory even have measures in place that publishers could use and it would still be a very big difference from a system where the default setting is that you cannot trade/lend/gift.