It makes sense for a wide range of densities. Getting MDUs is really nice, because your marginal cost to serve another customer in the building is really low. Downside is that it may be more competitive. Rural areas present a different business model, where you may have to go long distances and charge enough to support the infrastructure that requires. Single family homes in suburban/urban densities are right in between.

Each of the cases can work, you just need to make sure you're running the right kind of ISP for the market.