Blizzard has released a new patch for Overwatch that adds cross-play support for the console and PC versions of the team-based multiplayer FPS. Users just need to link their Battle.net accounts to their chosen device to participate. Other changes in the patch are bug fixes and hero updates. The update also adds region locking, which prevents players from choosing which region’s servers they want to play on. Blizzard explained that regions no longer exist, and the system places them in matches based on ping and skill levels.
The simple answer is, you are placed into the best match based on a variety of factors including player skill and ping. Getting more technical, it’s because the regions themselves no longer exist (at least not in the way players traditionally understand them), so there is no region to swap to.