Sure, dust will accrete, but it won't erode anything much. The only moving part that's exposed to this unfiltered airflow is the throttle butterfly, and I struggle to see how dust in a fast-moving airstream is going to find its way into the butterfly bushes. All the other moving parts are exposed to the dust to the same extent whether the carb heat is selected or not, so they are irrelevant.
You might get some blocked jets (although the air pressure is, by definition, pushing against the incoming dust rather than sucking it into the jets), but even if you did it would only need an overhaul (strip & clean) and wouyld not justify scrapping the carb.
So I still don't see it.
PDR