Very well put. I get flamed whenever I say that. But I guess its all in the wording.
So have I, but I don't give a chit its worth what people pay for it.

But I try hard to be correct and welcome anyone to set me straight if I screw up, sometimes I do type a little too fast.
Any half way good amp is like a power drill; a bigger one will drill a bigger hole faster...but any of them will drill a small hole the same. Some look cooler, fit your hand better, last a lot longer, are quieter, etc, etc. Making the sound is kind of the easy part with amps today, making it cheaper is the hard part.
Myself I only run amps, around 50rms/ch or more minimum. I'll have nothing to do with HUs or factory amps, I have not run a HU amp for over 10yr and only did that time because couldn't put a system in that car due to no time/location I was working/living....so I put my good HU in and slapped a powered 8" tube in back. Was a small car and actually worked ok, but certainly not up to my speed and not impressive. The system I have now is marginal and needs work, I'll get back on it once I collect all the parts for the next trial.
Amps are so cheap, heck I just bought a used 130x2rms on epay for ~$35 tmd and changed my mind, took it to a pawn shop and made $10 on it. So
why not use an amp? This was a middle of the road older amp, US company designed here Asian built, few scratches on it but worked fine. I tested it and it seemed to take a lot of current compared to some other amps I have and I didn't like that for a little car/alternator. Have a set of Kenwoods I can use for that project that seem more efficient and likely same quality. They are a lot of amp for the $. I would run a lightning bolt amp from walmart before I ran a HU, dirt cheap amp but they still work (until they break, lol).