The issue with having all the listings you manage and co-host affect your Superhost status, is that once you manage a couple of different properties, if one owner does something out of your control that affects your status (like decides that he/she needs to use the house and cancels a booking), you loose the superhost on ALL of your properties.
So if you have several owners on your own account and just one does something to affect your superhost status, you lose it on EVERY property.
As such, whilst I totally agree that co-hosts should get recognition, it is best that reviews and superhost is specific to a property.
As someone mentioned, maybe a co-host superhost category needs to be added (that would have limited impact on other properties if something went wrong).
This status could be allocated by the owner at discretion (some co-hosts only get involved every now and then when the owner is on vacation so it couldn't apply to everyone).
One thing that I do believe as a primary co-host is a problem is the lack of access to the background data that you get to see as the listing host - breakdown of performance ratings and feedback, occupancy levels etc. If you're managing the property as the primary host and it's you dealing with everything - you're working blind without this information (that is all available for the listing host who probably doesn't even know or care that it's there!)
I will be messaging airbnb regarding this...please do to!