As a non technically inclined end user I have never really cared too much about the numbers.
I understand their value to the marketing team but very early on in my career I discovered a Trace Elliot 130 watt combo was loud. Really loud and clear. Other amps with bigger numbers were not as loud. So I was lucky not to be seduced.
I now gig with numbers varying from 50, 100, 200 and many in between up to 2000.
The explanations above serve merely to muddy the waters even further for those like myself. That is not intended to deride the knowledge behind them, I simply can't grasp it.