Once again this thread has nothing to do with RNG.
It is just a special case, very easy to detect, more or less as probable (or improbable) as other tests that are performed in the signing process.
So why not?
Because you're wrong.
Ignoring potential problems with RNG, K=secret-key is no more a special value than K=11 (or 12 or 13 or any other specific value). All of them result in a trivally identifiable R.
Ignoring RNGs, you are no more likely to crack ECDSA by recognizing K==secret from R than you are to crack it by recognizing K==11 from R. You're aware that if the attacker knows K they can recover your private key, right? K doesn't need to be reused to expose you.