At the time of organizing iEra's rules, account sharing was generally prohibited due to the high volume of accounts being compromised by that method. However, this rule changed at some point to allow account sharing at the player's own risk.
The advice stated in the rules under "Account Rules, Guidelines and Safety" are for players who don't want to share their account and wish to secure their information from malicious people. That's why it's only a recommendation, not a rule.
I hope that clarifies it better.
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