It is a form of tracking. You're tracking if the user has adblock installed. Many people install adblockers for privacy do because they don't like being a part of data that will never be used in their best interest.
We're checking if the display of an ad is possible, but the only reason we're doing this is to inform the website owner of how ad blocking is affecting them. Once they have this information, a lot of good can come from it that would benefit all of that websites visitors.
You say a lot of good would come but I think it would just make them more likely to use aggressive adblock countermeasures so deflating their numbers is probably more in line with the best interest of adblock users.
The only solace I have that the only data the webserver will have is activity on that one server rather than all of my activity aggregated and analyzed by google or microsoft.
My response is also raising a question which I'd love to hear your thoughts on.