>But it is my understanding that it has enough fuel to do a full propulsive landing from orbit and back again, without an aerobrake.
Not even close. Dragon has something like 450m/s of dv to use. Getting from the surface of Mars to orbit takes 3800. Orbital capture requires around 2000m/s. Without aerobraking, it couldn't enter Mars orbit, let alone land.
Are you looking at the CRS dragon specs? It is absolutely the case that future designs of Dragon are able to do a direct powered ascent from Mars. That requires a lot more that 450m/s. Current dragon can't do that, but I wasn't talking about current dragon.
Not even close. Dragon has something like 450m/s of dv to use. Getting from the surface of Mars to orbit takes 3800. Orbital capture requires around 2000m/s. Without aerobraking, it couldn't enter Mars orbit, let alone land.