It is not allowed for the same reasons why gold selling is not allowed.
Your character is your own ingame avatar, and can’t be played by anyone else. Whatever you earn in game, you have to do yourself.
Otherwise, rich people would hire them a chinese farmer and get him to play his character all day long, possibly destroying the in-game economy and harms the competitive environment among players.
Thanks for the explanation. Got you
Is drug use against the terms of service? Could be that the person in question is just doing some kind of amfetamines… Hard to tell. 
It’s called account sharing and is against the rules. You can, if caught get a permaban.
unlikely because 1. still the person playing. 2. Blizzard can’t really prove it.
And hell if a person wanna use “drugs” just for a game … that person need help.
People use drugs jest for fun, so i guess its not unlikeley… 
Played some wow with americans before classic release, and apparantly the new brb smoke is now brb b0ng RIP. Proceding to ninjapull etc ofc…
Is he/she/it account sharing? Probably. Do I care? Not really.
Never underestimate just how determined someone is to level to max. For all you know, the person is sleeping randomly during hours you or any of your friends aren’t online.
Unless, you also have some sort of /who patrol who does nothing but to monitor the progress and online-status of said player.
Feel free to report in-game if you suspect foul play, Blizzard have tools to detect that kind of thing, but personally, I think posts like this just makes you seem petty.
Look at these cheating kids posting on level 10s with all their baby rage. Kinda proves me right already.
@galander
If you actually read the post I don’t say that he/she is cheating for sure. But if someone is farming the same mobs straight for 61 hours without even taking a nap that is fishy to say the least.
Also, there are a lot of determined people out there. There of world-ranked guilds playing 18h+ each day to level up, and this random dude with no guild comes up and gets ahead of everyone else by 6 levels?
I don’t know, still sounds fishy.
Hi. First of all, its 29. It means she hasnt sleep only in 2 days… not 2 month or even a week.
Second. You can share an account if you are Father/Mother — Son/Daughter.
Salutations.
Don’t underestimate the power of amphetamines…
Learn how not to be a snitch 
Maybe she takes a 30 min nap in between.
But you are not the police. Blizzard is. You don’t have any proof
Well, if they are doing as roommates, there no chance in seven hells that they will get banned.
Same IP, same PC, same account.
Maybe just a case of chronic insomnia 
Of course I don’t have any proof and of course I am not the decision maker here.
Maybe that’s why I am posting on the forums instead of banning him myself?
You aren’t that bright, are you?
ps: I see all the chinese mafia rage above. Made this a lot more fishy eventually.
to the guy above:
But if they are playing in different locations, they will.
Agree. Back in the days played with my brother on same account on same pc, because we were kids and we only had one subscription. Never had any issues.
OP irl 
I think that you can let your children to play on your account. So you can just make enough children to keep them busy 24/7 and force them to power level your character. Sounds legit.