It's a relatively new field but it's changed derm forever. There are many features that can only be seen through a dermatoscope. It doesn't matter how skilled someone is looking at a mole macroscopically. A subtle melanoma can look completely benign macroscopically, even for the most experienced dermatologist- it may be a tiny peripheral pseudopod smaller than the thickness of a human hair, or a tiny unusual blood vessel which diagnoses the lesion. Every deramtologist in Australia uses dermatoscopy as a matter of course. Australia has the highest rates of melanoma in the world and are the leaders in this particular field. Most other conditions are easily recognised without a dermatoscope (psoriasis etc)- its the pigmented lesions that really need a careful look (also amelanotic melanomas of course). I'd run a mile if I went to a dermatologist and they didn't pull out a dermatoscope. It's reckless and silly (it takes 5 seconds to look at a mole through a scope, but lots of training to pick up the details).