Never multiboxed on WoW, but I have on other MMO’s. It was fun, definitely harder than only having to focus on one character. Honestly enjoyed the challenge it added.
But those were all games that had some form of F2P model, I cant imagine paying $75 a month to keep up 5 accounts.
But really that is all beside the point. People have been complaining about multiboxing for the past 15 years. There was even another post about it 5 hours ago.
Short answer is Blizz has stated multiple times that it is not against ToS and a quick search through the forums, or a simple google search for “Is multiboxing allowed on WoW” will get you to all of the blue posts over the years about this topic. Even with all of the complaining on the forums for well over a decade they have not changed their stance.
But hey. . . Maybe, just maybe, this will be the post that changes their minds even though all it is doing is rehashing the exact same arguments as every other multiboxing thread out there.