Market focus allows you to only seek out investments exclusively in viable submarkets that have a future in your portfolio. By its very nature, market selection produces market elimination, which is a good thing because a narrow market focus means you stay in pre-determined geography. Advanced market selection eliminates "the chase" in areas with limited appeal.
Knowing your markets upfront is a competitive advantage because your competition is not as focused. When they look everywhere, you are looking deeper into pre-selected locations that you know well, areas that fit with your investment criteria. Superior market knowledge builds a significant competitive advantage because, over time, you know your markets better than anyone.