To start off with, I want to talk about using the core classes as a balance point. I can definitely see why you wouldn't just want to say "these classes are bad, screw them", but in reality can you really restrict yourself by saying that because Fighter and Monk exist, there cannot be any martial classes that out-class them despite their innate poor balance? Furthermore, if you really commit yourself to using the core classes as a base for power, what do you choose? A blasting sorcerer? An archer barbarian? A wizard focusing on Enchantment spells? Do you just go with 'what's popular'? The classes are so varied even within themselves that using _anything_ as a baseline would likely end up sorely lacking in scope, if you ask me.
However, moving past that, I want to respond to "or every group that knows the game inside out and can run numbers, there are infinitely more who haven't got a clue, who might only have had a core rulebook and a few others and hear good things about your product from word of mouth. Those are the people who will be hopefully buying your book as well. You should be catering to them to increase YOUR customer base. Not those of us who run numbers, and are going to buy the book regardless." in particular.
My experience to Pathfinder is, admittably, rather limited. I have never gotten to run a game in real life, and have only been involved in two or three online that have lasted past a month, as a GM or a player. I am, or rather was when I made the decision to buy Path of War, for all intents and purposes, part of the 'infinitely more who haven't got a clue'.
This is where my question lies - why would people not want to buy that book if they don't know much about the game? I don't really understand your point here, especially as someone who did just that. Path of War isn't only for experienced players to create more balanced martial options in comparison to spellcasters, it is very much also for newbie players to look over and say 'Hey, I love customising my characters and this book offers exciting and flavourful options for that!' without thinking of number-crunching for even a second. That's actually why I came to PoW - I wanted to make a cool 'noble duelist' character and found the existing options to be lacking.
I think Dreamscarred Press, while their product certainly is not perfect, does an admirable job achieving just that - catering to not only the players who do number-crunching and min-max their characters by offering (relatively) balanced options that help them keep up with spellcasters while still fulfilling a martial concept, but also to the casual players who look past numbers and look at fluff and 'what can I do' only - it does that in offering options that are just plainly awesome fluff-wise, and having content that is, and this is admittably based on taste, very easy on the eye and readable.
To add to that newbie friendliness, the PoW classes have a very comfortable power floor - it is hard to mess up a Warlord to be really bad, and infinitely easier to do so with a Fighter or Monk. You'll pretty much always be useful, and it makes for a fulfilling experience whereas playing Fighter or Monk without guidance will more likely than not end up frustrating in the end.
I can see the point that Dreamscarred Press shouldn't look past the new players in favor of the experienced ones that do number-crunching, and I can see how they shouldn't alienate customers by completely dismissing all other martial classes.
I just can't see how they're doing that with this book.