What is the exact reason for xbox pc seperation ?

Let me preface this by saying yes, I get that mouse keyboard players have an advantage but isn't this purely a PVM game ? I couldn't find any reason not to merge both bases into one except for the one above.

Alone the patch problematic would be a big issue. You cannot ask now all the pc players, to wait for hotfixes, till the xbox patch is ready as you couldn't run different versions anymore. Also Xbox would need to be on the same level as pc, like for trading. atm, it supports trading without the need of multiplayer, if it would have the same version as pc, it would need f2f trading, which would force people to buy xbox gold. So many complications.