Again with the equating marketing to communication, propagation of ideas and persuasion. What goes on in a classroom is not marketing, by any useful definition...
Any time you have limited attention, and more than one idea vying for that attention, the end result is marketing.
Any argument you make that students should spend an hour learning about quantum mechanics instead of something else on the market of ideas (eg. finance, literature, history, etc.) is by definition an act of positioning.
The curriculum of today is the result of marketing in the past. You just don't see it that way because you weren't around when those decisions were being made.
No, you're defining marketing in a way so broad as to render the term meaningless, as a way of avoiding answering the actual criticisms. An extreme example of this kind of argument would be "murder is doing stuff, here is an example of people doing stuff and it's fine, so murder is fine". This is fallacious (and, if done deliberately, dishonest) so I won't engage in that line of debate further.
Yet.