1. IAD’s runways are 10-12000 ft, DCA’s is 6870 ft; that’s a very substantial difference in terms of margin should the jet “float” and land a couple thousand feet beyond the normal touchdown point
2. IAD’s crosswind runway (12/30) is 10000 ft, whereas DCA’s 15/33 is about half that length

I’m pretty sure an A319 can land in 5000 ft under nominal conditions, but these pilots were dealing with anything but nominal in terms of both wind speed and direction (to say nothing of how much and how often they varied)