corsair vengeance 2666 not recognized properly by z390 board

Hi ,

with i5 9600k and a z390 board ( which support natively 2666 ram ) , if I set ram on auto , motherboard set at 2133.

Someone told me it's because of jedec spec in the SPD chip.

Only way to set at 2666 is via XMP.

Obtaining 2666 via xmp can be an issue ?

Why they don't make a jedec 2666 module ? I know they exist , like xyperx fury.

I don't get it , considering that corsair vengeance 2666 xmp profile leave voltage at 1.2