While I tend to agree with this, it's kind of adorable when a far-too-young dragon tries to extort tribute from a high-level party and they try to figure out to resolve the confrontation without violence. (Bonus points if the too-young dragon isn't relying on family connections for intimidation value, but the well-informed PCs know that the youngster is connected to (and would be revenged by) a much older dragon.)Oh, I thought of another thing that bugs me: disposable dragons.
If your players aren't visibly terrified when facing off against a dragon at your table,
if their voices don't lower to a nervous whisper,
if they don't lean forward in their chairs rapt with attention,
if they don't immediately start planning an exit strategy "just in case this doesn't go well," or "just so one or two of us might survive,"
...I'm talking to you and your overgrown lizards.