They use it to drive hits to their website so their website will rank higher in the searches.
Yes, it is annoying as hell but less so than all the private sellers who don't even tell us what state they are in, in defiance of the rules.
Best to just ignore those dealer ads completely. There is an old saying "if you have to ask what the price is, you can't afford it", so if you have to beg for a price or click 2 or 3 links to find it, it's probably priced too high anyway.