Oh so very much this. The assumptions made about how PC vs. monster resources are viewed paint a very clear picture of combat as sport that just leaves me much less interested in the whole deal.
Expected "fights per day" is craptastic design at its very foundation and needs to go away.
And you as an individual DM are more than able to have that "craptastic" fights per day design go away. Nobody is saying you have to use it. It's there for everybody else who wants a pretty solid idea how many fights a party can go through with the resources they have. But if you want them easier or harder, go right ahead.
But if you're getting p.o.d because the designers are actually telling us how the numbers are set up so that these "fights per day" can be calculated... you need to stop reading these articles that talk about them. There's nothing wrong with keeping your head in the sand about the underlying design principles of the game if you don't like seeing how the sausage is made.
Cause if you don't think that every other edition had an underlying math, you're fooling yourself.