Whether you agree with the title "PC Master Race" or not, there is no denying that PC as a gaming platform has a lot to offer. It allows developers to create games bigger than anything on consoles and manage them more easily.
That means when a competitive community starts to grow around a game, developers have better tools to foster it. Consoles don't give them the option to grow the game in a consistent way with updates and expansions the way PC can offer. So their competitive scenes struggle to keep up.