[SomeoneFromCA]

Because what you are describing is a simplistic picture, describing whole class of people as stupid simpletons who cannot tell low THD and low IMD audio from "soft clipping which sounds nice". If you are referring to vacuum tube amps, soft clipping is only partially the reason why they sound the way they do; in fact most of the time amps are not clipping and are outputting close to 1% of their their total power. Reasons why tube equipment sounds better/different from the solid state amps are a lot more complex than the "common wisdom" of soft clipping.