This is of course gross oversimplification, but do have a point:
a) Just like the Megaherz wars in computer space or more recent quantity of cores - Simply stating power capabilities without knowing how it was measured is useless
b) Only few dBs in Speakers sensitivity will have greater effect in loudness than extra 50 Watts of amp power
c) and neither of these has of course any effect on clarity
I could go on