[morzh]

We discussed that before, one only needs a few watts to listen but to produce undistorted peaks the wattage potential should be large. The today's music has way more of those than the music of 30s-40s, or classical one. Back then an amp of a few watts would produce loud enough unclipped sound, whereas today you listen at the same few watts loudness (if that much) and a short peak with steep attack goes to momentary power of tens of watts. If it gets clipped your sound degrades.

One might think an amp could be designed that can have rated power of a few watts while the peak power could be made very high, and this is true, that can be done. But to me the potential problem is that if a fairly mindless person learns an amp can produce large power he might be tempted to use it constantly at that level, and this will kill the amp.
Hence the power wars.
A normal individual will listen comfrtably to a normal loudness level, but should a brainless youngster decide to put the speakers outside and deafen everyone for an hour, or damage a house's structural integrity, the amp will survive.