Imagine somebody handed you a theoretical amp that had the perfect gain structure for you, perfect gain texture, best gain adjustment through the sweep of the entire gain knob(s), best compression or lack thereof, best clarity for you, best poweramp behavior... but the EQ knobs didn't behave in a way that suits what you're trying to do. You know you will never find an amp with better gain for your style of playing.
Do you throw the baby out with the bathwater because only part of the amp is perfect for you, and instead buy a different amp altogether with a better tonestack but worse gain characteristics? Or do you put an EQ in the loop?
What if guitar gear was made differently? What if instead of everything being contained in one big amp head, the preamp gain section came in its own individual tolex box, and you plugged it into a separate EQ section which was also enclosed in its own tolex box, which you then plugged into a dedicated power section, also enclosed in its own tolex box? Would you look at the question differently?
What if amp heads and 4x12 cabs came built together like large combo amps and the concept of the separate speaker cab was never invented? Would you also refuse to ever consider changing out the speakers to something you liked better because the speakers are "part of the amp" and if the speakers aren't great then "the whole amp" isn't just isn't what you're looking for?
Imo it's limiting to think of an amp as the smallest unit of tone generation in the chain. If you think of amps as singular all-or-nothing magic black boxes that either are or are not exactly what you want in every way, you'll miss out on a lot of possibilities for yourself. If you treat amps more like collections of components in the chain that happen to come in one box, it becomes easier to see what you need to do to get the sound you want.
