Today (a few days after making all the accounts) I got the idea of logging into each of my other reroll accounts to see whether I can get anything decent on them with the free 10 pull daily but after logging into them and attempting to play the game I'm greeted with a message stating "the account is not entitled to play Granblue Fantasy".
It then has a wall of text stating the possible reasons for this, one of which being overloading the servers.
I'm not entirely sure whether skipping the tutorial would do much harm to the server but I suppose it adds up when you reroll so many times.
They didn't ban the account that my friend is using, so I'm assuming they only ban accounts that are not used after rerolling - maybe because they suspect it's a bot account or something.
I can't be sure of whether tutorial skipping is the reason for this, they mention that that they will not disclose the reason for the ban or give any details on whether the ban will be lifted in future so I have no way of finding out the true reason for this but I do suspect it is due to overloading the server.
This had no effect on my main account or the account I gave to my friend even though I used same email for every account (salted) so I dont think there's much risk involved but it should be noted that there is potential to be banned when rerolling.
Here is the message I'm greeted with:
お客様は現在、「グランブルーファンタジー」を
ご利用いただくことができません。
アカウント停止措置が実施される主な理由としては、
下記のような行為が挙げられます。
■本サービス、及び、mobageのサービス運営・提供を妨害する行為
・サービス内で定められた規約やルールに違反する
・サービス外で提供されているツールを利用してサービスを利用する
・金品や金券、及び、他のゲームのアイテム等と取引する
■他のプレイヤーが利用するゲーム内情報に不当に損失を与える行為
■実体の無いアカウントを大量に作成し、ゲームバランスに悪影響を与える行為
■運営事務局で認めていない方法を用いて、
定期的且つ継続してサービスに負荷を与え続ける行為
他にも、mobageを運用しております株式会社DeNAの規約にて禁止されている行為が確認された場合、アカウント停止措置を実施しております。
なお、お客様のアカウントに対し「アカウント停止措置」が実施されたことについて、実施理由や実施期間等はお伝えしておりません。何卒ご了承ください。
I tried 12 of my reroll accounts, all of them have the same message and I can't be bothered to check the others but I'm sure they're the same. The only difference between these accounts and the one my friend is using is that my friend's account is actively being played on while all the other reroll accounts I made haven't been touched until today.
So, TL;DR: If you don't want your reroll accounts to be banned, make sure to actively login to them.. I guess?