While I sympathize with your frustration, this is the same question we were asking at the fin de ciecle over Duchamp's Fontaine over "is this art?" - and has been repeated in "what is theatre/fiction?" "Is borat fiction?" "Is an advertisement a movie?" "Are documentaries neccessarily non fiction?" which leads you all the way back to epistemology, the Socratic method, and a state of aporia.

The only reasonable conclusion is "if anyone says it's a meme it's a meme"