It's still a good reason to buy one that has more power than needed, because the correct way to EQ is to reduce the volume of frequencies you don't want to boost, and thus you end up having to listen to your headphone "louder than necessary". Note: by this, I mean you have to increase volume, or everything that you EQ'ed down would sound tinny.
I didn't say otherwise. Although a Sansa Clip+ will drive Fostex TR50 studio monitors or HD25-i-iis to ear bleed levels, so add-on amps aren't useful nearly as often as people think.
But EQ doesn't take away the characteristics of the headphone.
It certainly "takes away" the frequency response; that's the point!
You still need more power to increase volume. Since sound pressure level is measured using a logarithm function, it takes a lot more power to go up by just 1dB.
Once again: a tiny $30 Clip+, EQed, will drive Fostex TR50s to "Your brain will be pulverized" levels. The actual amount of power needed to drive most headphones is easily provided.
Why do you think people need something as powerful as the Schiit Lyr?
That would depend on the person. If you are arguing that it should be assumed that people on this forum should always be presumed to be intelligent and knowledgeable, I am going to laugh at you.