Welcome to open world combat. There are plenty of instanced missions in the game. If some random player comes along and tags your target in Atlas Park, just roll with it. Anything n the streets is fair game and as it's been said, there are plenty of targets to choose from and they don't take long to drop. Now if it was an elite boss or Arch Villian/Hero that was mission critical and took 10 minutes to respawn, that'd be different, but come on. Getting bent outta shape over Skulls, Thorns, Hellions, and Freakshows that are running rampant on the streets, that's a little over the top.