I think there are pros/cons to getting into dermatology as an MD versus a DO. MDs can match 4th year, and so it's more of a straight guaranteed path, and as a DO, it is virtually impossible to match at an MD spot. But the odds of being competitive in derm are super low as an MD as well...some combination of 250+ boards, multiple pubs, honors on most rotations and AOA are typically things needed to be competitive...I mean, probably only ~5% of MD students could even consider derm as a potential specialty based on these sorts of barriers alone.
At least the DO world has more routes into the field- I.e. things like a fellowship from IM/FM, proving yourself intern year etc., but there are cons to that as well. Correct me if I'm wrong, but it seems that boards/honors/AOA etc. are important, but not quite as important, to match DO derm, since you are completing an internship and/or entire residency before you are even eligible to apply. So it seems your skills/work ethic/charima/personality probably play an equally important role to securing a spot as numbers. On the other hand, the point that I was trying to drive home earlier is that someone who has their heart set on DO dermatology after completing intern year or after a FM/IM residency, is probably not going to be happy stuck in an AOA primary care specialty if they aren't able to succesfully match into dermatology after this...