But if you put a monkey in a cage and reward him for raising his right hand/paw, why would he care about raising his left?
The two objectives started in the same place, but they have since diverged in ways that now leave them diametrically opposed.
In the first days of "creativity", every molecule of intelligence, lateral thinking and originality was expended in pursuit of the sale or the brand-build. But as "creativity" developed, confusion arose: if ads that were harder to get were better, wouldn't an ad that was virtually impossible to get be the apex of quality?
Over the years, every step in the wrong direction devalued every step in the right one. Creativity began to be dismissed as indulgence and this theory was only compounded by the success of ads that continued to smash the consumer over the head with the dumb and the crass.
But advertising awards were created and were given to the work that attempted quality, with little or no interest paid to quantity (of sales). So the raises, promotions and kudos have gone to the creative pioneers, not necessarily the great salesmen. And that's the 100 per cent logical reason why creatives have no incentive to care about effectiveness.