I'm a little late with the news, but Activision-Blizzard announced on 5 May 2021 a ban to all input broadcasting in World of Warcraft.
On November 3, 2020, we posted an update to our policy for input broadcasting software, and soon thereafter, we began taking action against accounts found to be using third party software to automatically mirror keystrokes to multiple game clients. We find that, like full automation of play, multiple-account mirroring disturbs the gameplay experience for the vast majority of players who control a single account at a time.
We will now additionally prohibit the use of all software and hardware mechanisms to mirror commands to multiple World of Warcraft accounts at the same time, or to automate or streamline multi-boxing in any way. Players found to be in violation of this policy are subject to account actions. These actions can include warnings, account suspensions and, if necessary, permanent closure of the player’s World of Warcraft account(s), as activities which effectively replicate automated gameplay are contrary to the terms and conditions of the Blizzard End-User License Agreement (EULA).
We urge all players to cease using any means of mirroring gameplay across multiple WoW accounts immediately, in order to maintain uninterrupted access to World of Warcraft.
Whether players use hardware or software to send keystrokes to multiple accounts doesn't matter anymore. The move should make enforcement much easier. Instead of having to use technical means to determine whether a player is violating the rules, all a GM now has to do is see whether the actions of multiple characters are synchronized.
Joe "Lax" Thaler, the creator of the ISBoxer multi-boxing software, wrote on the Dual-Boxing.com forums on 6 May:
Realistically, they were already banning for the things they are describing in this updated policy.
I warned about this in November. As I said back then, there is zero difference to other players between you using software or hardware broadcasting. There's no way for a player to make that determination. And I would guess that Blizzard (and particularly random GMs) probably cannot make that determination reliably either. Even if they could, the next question is, do you really think it is worth their time and energy to determine that?
Since November, we've seen random people come to our multiboxing chat rooms (about once a week or so) and claim that they got banned "for using X software" (which many other people use on a daily basis with no issue). Then they show their ban email, and it says "Your fellow players reported you for cheating". When pushed on what they're doing, it's almost exclusively "I was 2x4 herbing, and 'only for 4 hours a day!'" and one recently even says he was hardware broadcasting.
Other players do not like to see "multiboxers" doing "2x4 herbing". They will report you, have no clue if you're using software or hardware, and frankly they never cared in the first place.
I think the latest effort is serious. Thaler is developing a new software program called Joe Multiboxer that does not perform input broadcasting. He thinks his software is safe for now.
They didn't say, so how are we to know what they are banning for exactly? Again, my interpretation is that they were already banning for the behaviors they wanted to ban for. They say multiboxing is allowed. There's no specific reason to believe that they banned Joe Multiboxer yet, but it is unclear what they mean by "streamline in any way", it could literally mean anything.
I will continue to use and develop Joe Multiboxer under the current policy. However, I would advise not using Round-Robin, as that would seem to fall under "streamlining".
The use of multi-boxing software incorporating input broadcasting is a pretty old issue. Most games just outlaw the practice. EVE Online, while not banning the use of the ISBoxer software, banned the problematic features on 1 January 2015. Because of the history of Inner Space, ISBoxer, and multi-boxing in general, covering a story in WoW is just a follow-up of a formerly hot story in EVE. One, hopefully, that is coming to a conclusion.