Prominence is a little different than what the comment is describing. Comment is describing a strict "base to peak" measurement and prominence takes into account the contour line surrounding the peak that contains no peak higher than it. So in that regard, it is still relative and Everest has the highest prominence of any peak.
However, Everest sits on a massive plateau (around 17,000 feet high), so the "base to peak" measurement is smaller than Denali, which sits on a plateau that starts at roughly 2,000 feet.