How do you preempt the “X already does that” reaction? (I will not promote)

I’m taking a few products to market right now, and the single most common response when I describe one of them is some version of “but X already does that.” Reddit is the worst for it, but I get it in person too. I know it shouldn’t stop anyone. Taken seriously, it’s the argument for a world with only Ford cars and Coca-Cola. No market worth entering is a blue ocean. My problem is what it does to the conversation. I’ve spent months on positioning, they’ve had five minutes of intro, and the first thing I get is a weakness I’m already aware of. I know it's not a blue ocean market. I feel the irritation rising, I go defensive, and the conversation is dead. That’s on me, and I’d like to stop doing it. So I’m thinking the fix is in the pitch itself: name the incumbent before they do, say what’s wrong with it, and lead with my angle (a, b, c) instead of the category. Something like “people use X for this and hate Y, we remove Y.” But I’m honestly not sure that’s the whole story. Is “X already does that” usually a sign that my pitch failed, and I should fix it? Or is it mostly just a reflex from a certain kind of commenter, the one who always needs to pull something down, and the right move is to nod and move on? How do you tell the two apart in the moment?