Marketing job definition

Those of us in the marketing industry I am sure are well aware of the travails of defining a true marketing position within a company. Currently I am on the job hunt for a marketing position, and a majority of companies lump marketing along with sales positions, seeing the two as one in the same as far as functionality goes.

Why is it that businesses still fail to understand the true role of marketing, and the benefit of a marketing department separate from any other internal entity?

Not only does this frustrate true marketers and add to the "sales and marketing" title confusion, but I believe it also adds to the problem of marketing with the consumer in mind- reverse marketing.

Sales do in fact play an integral part in marketing functions; but the key to that statement is "part". Sales are but a part of the marketing equation that forms a successful strategy- centered around the customer of course.

Another piece to the puzzle that forms the phrase "reverse marketing" as I try to define true marketing from what it is known as today.