I've started to see quite a bit of that on websites dealing with transfer of medical data. I figured it was probably some sort of an effort to handicap MITM pot

I've started to see quite a bit of that on websites dealing with transfer of medical data. I figured it was probably some sort of an effort to handicap MITM potential of impostor websites that were trying to steal credentials. My theory is that it might be some sort of a tripwire for the website to detect fishiness and lock the account.