Marketing is different
In short, marketing is the art and science of wrangling with uncertainty.

Marketing?
Marketing (and innovation) are remarkably different business disciplines to any other function in a commercial organisation.
The best (honest) description of marketing, that we can come up with, is:
'the skilled practice of selectively choosing how to spend an astronomical amount of budget, building an intangible asset (the value of which cannot empirically be measured), the mental image of which resonates in such a profound way as to convince people, you have never met before, (whose future preferences are uncertain and over whom you have no control) to pay money for something at a price point that is higher than what you acquired it for yourself. Repeatedly.'
In short, marketing is the art and science of wrangling with uncertainty.
The practice demands that important choices be made under conditions of uncertainty, competition and constraint in order to achieve a desired future outcome.
But unlike every other business discipline, there are no facts to support the options selected.
There are no data to confidently pin down what potential customers will want in 6 months time.
You cannot be assured that investing in one creative advertising idea will deliver more customers to the business than the alternative.
It's not always obvious that a major change is on the horizon, that will impact the behaviour and preferences of important agents in the market place.
Marketing choices require a judgment to be made between different plausible arguments based largely on conjecture.
When less than ideal amounts of money are being spent on marketing, it's usually because the arguments supporting the investment are not strong enough.
Progress depends on presenting a strong case, a good argument for the right action.
More like LA Law than Mad Men.