Care to explain why you disagree?
From a purist/technical standpoint, because according to the Istituto Nazionale Espresso Italiano, the definition of espresso is
That said, I don't consider the technical definition of an Italian espresso to be the only legitimate one, nor that of the SCAA:
Espresso is a 45ml (1.5 ounces) beverage that is prepared from 7-9 grams of coffee through which clean water of 192¡ - 198¡ F (88¡ - 92¡ C) has been forced at 9-10 atmospheres of pressure, where the grind of the coffee has made the brewing "flow"* time approximately 22-28 seconds.
While brewing, the flow of Espresso will appear to have the viscosity of warm honey and the resulting beverage will exhibit a thick dark gold cream foam ("crema") topping. Espresso is usually prepared specifically for, and immediately served to its intended consumer.
The reason I actually have a problem with calling AP/moka coffee "espresso" is because it is a drink that is sufficiently different from what would generally be recognised (worldwide) as espresso, in flavour and in texture, so as to require a distinct and separate term to describe it. If what came out of an AP/moka pot was sufficiently similar, I wouldn't make a point of it.
Espresso is polyphasic, relatively viscous, it has crema, (which is a stable emulsion, not just froth, and feels/tastes different to the froth on an AP), it is significantly more intense in flavour, and it can have flavour profiles not attainable in AP/moka coffee (for instance, intense natural sweetness).
tl;dr - Because espresso is a very different drink, and there is value in distinguishing it from AP coffee in conversation, much like how there is value in not calling a sandwich loaf a "biscuit"