I don't see how it's not a technical challenge. They don't have to dumb down the game or have exclusive maps for the console versions, they could do a direct port.
Edit: especially when the guy on the forum complains that it would make merges more difficult. Keeping the code base seperated for the console versions sounds kind of technical.
Edit2: well, if he just means ps4 vs.xbox, then it's obviously Microsoft's fault, but there's no reason ps4 players shouldn't be able to play with pc players.