Despite the current matchmaking bugs the system is actually designed to throw you into others regions or throw out of region players into your region if the matchmaking pool is deemed to small.

The system is meant to match you in your current region primarily. To try and help with matchmaking times in th event of the matchmaking pool being too small the system will match you to your "next best" region if there are not enough players in your closest region. The system was never designed to lock people into their own region, nor was it designed to prevent others from playing in someone elses (otherwise you wouldn't be able to play with your friends who happen to be elsewhere). Some players are finding that they are frequently being placed out of region and have high pings as a result. This has been reported to the team to be looked into further.

  Confirmation from a mod on the pubg forums: https://forums.playbattlegrounds.com/topic/294460-transparency-regarding-matchmaking-please/?do=findComment&comment=1073278