Spam always happens in all markets unfortunately and its not always about reputation points (however is a side affect on CGT). Its usually about drowning out the competition in that search result and/or taking advantage of new 3D artists who don't know how to use basic functions like color correction/hue adjustments. It also has an affect on the search algorithm in some way or another, its a bit of an anomaly but from my own experience I've noticed the more often I'm uploading models the more often I'm selling, just my observation.
I don't know if its against the rules however I agree its not good for buyers or sellers so hoping this becomes something that can be flagged in future since it does happen quite a lot and is really arrogant behavior.