Hello @Deborah56 ,
Airbnb is not specific a platform for long term stay (reservations more then 28 days). So the rules are mainly setup for the majority of host, whith reservations for short(er) periods. It's also more difficult to manage the superhost statistics, as also the lenght of stay has to be measured related to the amount of reservations.
But the way you describe it shows that it is indeed unfair, as you simply don't have the opportunity to become a SuperHost. I personally don't bother about this "Superhost" status, if would even suggest to Airbnb to present an option to decline or accept it, when it's granted !
Best regards, Emiel