How is it bad for the game, if the player doesn't shave his own teammates from gyms?
It opens up a can of worms.
Your own question has the answer...their needs to be a lot of *IF* to ensure there is no grey area, and where there is grey area, someone will always look to go over to the dark side.
To avoid the grey area, they make a rule against all multi accounts.
I am not voicing an opinion on multi accounting, I am simply speculating on why Niantic would make it against their rules.
In my Discord group multi-accounting has become common. It started with a few people shyly saying they brought their wife's account. Now, its pretty common for people to openly say they have a second account. I can see the appeal to having one: not enough people for the raid, just whip out the alt-account; gym all full of demotivated same-team mon, just whip out the alt account to make a place for yourself; need some coins, just knock yourself out of a gym.
Recently, one of my raid mates was delighted to give his mewtwo focus blast. It seems his delight was that now he can shave healthy blissey and snorlax from gyms. So, often I go to the trouble of taking a gym down, putting a blissey in it to hold it down, only to get shaved out by him before I get my coins. His excuse is he is busy and doesn't have time to take down a whole gym, or grind to stock up on potions.
I think this is pretty unfair, and also bound to happen given that having multi-accounts is openly tolerated. To be honest, I'm tempted to start a second account so that I can shave him back out of gyms, but I'll continue playing by the rules.
Interestingly, the same discord group doesn't tolerate spoofers.
Multi accounting is extremely common in my small town raid group. Some times I'm ok with it. Depending on the situation. As long as there's an actual person to represent the account it's not too bad. But when it's an account for your dog. Or a child too young to care about the game
Side note: sometimes a second account can come back and bite you in the ass. Our local level 40 started a second account and did alot of raids with it. Which resulted in his second account getting the ex raid invite instead of his level 40 account
I have two accounts in the same team. Started the second account last year to fill an extra space in gyms because I liked training up gyms really high.
In the new gym system, I am very conscious about watching how long defenders have been in gyms. Except for gym control for raids, I generally leave gyms that are less than 8 hours alone, and sometimes go out of my way for gyms that have more than a day. More importantly, I do not hoard more gyms than I need for my daily coins.
Have been considering for a while starting an off color account and building it up just enough only to knock my own stagnant defenders out of the first position of a gym when I need daily coins, but I don't want to be tempted to use it for other means.
It is a slippery slope. There are other people in my town that do not care about other people's time in gyms and they take as many gyms as they can. Some are either different people that always play together, or multi accounts. If they are individual players, they are allowed to be as disruptive and annoying as they want. Being a jerk doesn't break the TOS. But I am much more considerate with two accounts and get my max coins most of the time.
Edit: Someone doesn't like that I watch the time that other players have been in gyms and only take enough gyms to eke by my daily coins. If I had only one account but constantly kicked every other team out of every gym I passed, would that be more acceptable? I certainly have enough potions that I could do that. *shrugs* whatever.
There is a player locally who has at least 5 accounts. Usually puts at least 3 in a gym when he takes it over, sometimes more. Started doing it under the old gym system and has continued.
It's merely annoying being on a different team, but I can't imagine what it's like to the players on the same team encountering full gyms. Probably encourages them to get more accounts.
