Although I find the notion of philosophy being like "the creation of concepts" rather limiting (philosophy can be this, but much more), if we stick with this no

Although I find the notion of philosophy being like "the creation of concepts" rather limiting (philosophy can be this, but much more), if we stick with this notion, I still think it's not entirely correct. If philosophy were to create concepts, then the question immediately arises of how one would determine whether these concepts were created correctly, or truthfully. The understanding here is that concepts are universal, and not contingent on anything, including on how they were "created". Instead, I think Deleuze should have defined philosophy as something like "the discovery of concepts, a discovery that, once accomplished, reveals to us something we had already known." Full disclosure: I'm defining concept not in the regular, everyday way, but more in line with Hegelian, Idealist way--der Begriff.