I disagree, because:
Firstly, what's your definition of a "big" idea? Does it mean, ideas and thoughts succeeding after endless nights of research& reading, experience and money or does it mean the silliest idea succeeding without any expense/time forthwith growing to become a "big idea" or does it mean a simple, articulated, and ordinarily pitched-idea, with growing impressions to be called a "big idea"?
Secondly, there is no single way of "coming up" with an idea. For some, it's a 100-yard swimming pool ready to swim into when the whistle blows, hence a pre-defined huge space of mind, but an emphasis on the huge space; for some, it's picking the right shades of Pantone pink (scarlet, magenta or crimson), hence thought and executed with perfection; and for some, it's simply daydreaming while dipping a biscuit in your milk while it melts in and a plop! the idea lights up like a bulb, a relaxed, casually brainstormed idea. These are just a few ways, but each of the types has either less education/ high exposure/ hangover.
Thirdly, if it all subjective, then why do we ignore the above? People really underestimate each other for being good at "coming up" with ideas, because no two human brains are similar, some draw inspiration from our old-fashioned, vintage, long copy for a Volkswagen Fastback Sedan, and some spur from the thoroughly researched ambush of McDonald's by Burger king, or some prod towards creating a cheeky post for Durex, or some choose the pursuit of purpose whereas some simply remix content because its the new "cool", there are endless quintessences of how people create and to compartmentalize that creation of art into a big or small idea is why we suffer a downside of the pay gap in all Industries vs. Advertising. So this concept of having a "big idea" outrightly negates the whole argument and makes advertising more submissive. This roots from the argument how monetizing art has made itself inauthentic and worthless.
Thus, ideas can never be encircled ascending from huge concentric circles of different diameters or categorized into "big" or "small", people should be left to decide that because we are only deteriorating our worth by confining our ideas.