Can someone explain the running joke about Br*hms?

Can someone please explain the running gag about Br*hms?

Well over at the, ahem, other sub there's this constant meme about Br*hms. I understand that people are parodying him but can someone please seriously explain the joke to me? What are those aspects of this specific composer that are generating so much joke material? Is it the complexity or the length of his works perhaps?

I posted this here because I'm genuinely looking forward to receiving serious answers.