Row houses often become more expensive row houses. It may not be the bulk of "new" housing in DC, but you asked where it happens, and that's where. So, chill.
In any case, gentrification, infamously kicked thousands of families out of projects, subsidized housing, and regular rentals, replacing them with... definitely not affordable housing. Rent has only gone up. And unless you're a builder, the goal is not building, it's only a means to the end of putting people in affordable homes. If building isn't doing that, it's a policy failure, and other avenues need to be pursued.
In any case, gentrification, infamously kicked thousands of families out of projects, subsidized housing, and regular rentals, replacing them with... definitely not affordable housing. Rent has only gone up. And unless you're a builder, the goal is not building, it's only a means to the end of putting people in affordable homes. If building isn't doing that, it's a policy failure, and other avenues need to be pursued.