Part of the Rules says:
§ 1.3 Sharing account passwords is not permitted, except in the case of "dual accounts". "Dual accounts" are accounts played by two or more players. This is permitted as long as none of the players involved either own or play another account on the same game world. If a player wishes to move from one account to another, the ownership of the first account must be transferred and the password changed BEFORE access is granted to the new account.
The word "dual" usually implies two but the rule says "two or more" without a limit. As a result, we are now seeing teams of 4, 5, 6, 7 or more people sharing a single account. They play "shifts" so the accounts are active 24 hours a day and are usually highly aggressive.
This represents an unfair advantage to the great majority of players who are single players and do things like sleep, eat etc.
§3 of the rules says it is forbidden to use external programs and scripts or bots. One reason is obvious: it allows users to keep the account "working" when they are off-line.
I would say allowing "teams" of people to run a single account is the equivalent of using scripts/bots in the sense of the effect it has: the account is active in an abnormal way - abnormal for normal, single players.
A limit needs to be put on the number of people who can operate a single account, to keep things fair for everyone. In rule § 1.3 where it says "two or more", the "more" should be quantified.