There does seem to exist a particular breed of "intellectual" who not only confuses the two, but seemingly believes that conceptual understanding is merely an unpleasant side effect one must endure in order to achieve the ultimate goal, which is to grow one's vocabulary (and grow it beyond recognition, and, more importantly, beyond scrutiny from mere-mortals).
Jargon creep is inevitable when we go expert-crazy, which, it seems to me, is more about marking territory and protecting one's clique than any legitimate concern for the advancement of knowledge.
> "It's simply no longer possible to be an expert in more than one field."
This is a lazy straw-man argument (1).
Of course, experts are necessary, and we'd only go so far before we start running in circles if not for dedicated individuals... But how does this negate the value of polymaths?
This is like saying that wheels on an airplane are completely useless, because wings have been meticulously crafted for the sole purpose of flying. -- The two serve different purposes. The plane can't fly without the one, but it won't get off the ground without the other.
A polymath will never acquire the depth of understanding of an expert, but neither can the expert have access to the more varied sources of inspiration / patterns of thought that a polymath acquires through breadth of experience. It seems obvious to me that the two personality types complement each other (like "the two cultures" -- problem solvers and theory builders).
If anything, given the insurmountable amount of knowledge we've gathered on any given topic, now more than ever we need to actively research more effective means of cross-pollinating, or run the risk of academic myopia.
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(1) or maybe not a straw-man... a red herring? We might need to bring in an expert in argumentation theory -- preferably one with extensive research in the field of informal fallacies -- as I am clearly not qualified to comment one way or the other.