I think this is meant in another way: sales and marketing should never discuss future features with potential customers. Meaning, they should not try to win deals by promising features not yet rolled out, rather than not being involved in internal priorization discussions.

I happen to agree with the author to an extent. Selling future things rather than what's presently available makes sales a lot easier (which is why reps are often eager to do it), but the true value is created when sales sells what is already there. My father always put it this way: You have to sell what you have.