I took him saying "just wrong" as being "im not OK with this", but i could be incorrect.
However, with that said, i have always found that calling your rep and asking about specific un documented limits is the fastest way to get to the bottom of per-instance/account/vpc/whatever limits.
Just as there are limits that can be changed if you agree, in writing, that you will be financially responsible for whatever the impact is (e.g. when you could tell them that you wanted spot price limits adjusted for you to be able to better bid above the scaling factors that were in place(not sure if this is still the case))
Some limits are global and cant be changed/negotiated, but other undocumented limits....
Do you have a more accurate dataset? What are your observations?
I'm assuming this affects loads of HN readers and I too am interested in what the facts are.
Side note: you may be getting downvoted because a source, or other details are lacking. I too get downvoted for posts that lack these details.