The poblem is X1 and PS4. You can't give X1X owners an advantage in a competitive PvP game. All console versions must be the same across the platform.
And siknce one of their goals is a seamless transition and shared experiece across PvE & PvP then MP will be reestricted to what PvE can do.
Technically I have no doubt all the current gen systems could run MP at 60fps.
Yup, and unfortunately the X1 is holding back all consoles and PC because it's the weakest. Look at PUBG, it's going to suck on console because the X1 is holding it back at 30fps just like Destiny 2. Real oversight on Microsoft's part, trying to break down walls and killing off generations but still supporting a box that struggles to do 1080p/60fps.