This seems like a very "um, akshuallyyy" response. There IS a cookie banner law. If the law says, "You must do X before doing Y," and you know that everyone is still going to do Y, you've effectively mandated X. The argument that simply not doing Y (which everyone does, and which you need to do to avoid being at a competitive disadvantage in the market) would avoid the mandate to do X is a pointless technicality.

Regardless of whether cookie banners could technically be avoided, Graham's point stands that this regulation has served no purpose other than to annoy consumers.