"If errors in a tree was grounds for keeping a tree private then most trees should be private."
"Are you referring to the last comment I made? If so, please read it again because I merely pointed out that we all have some errors and by comparing we can fix them."
Although we all probably do have errors in our trees, your 1st comment above mentioning "grounds" for privatizing trees with DNA test results attached indicates a person having a private tree and completing genealogical DNA testing needs to explain the reason(s) for making their tree private.
I've done DNA testing and have a private tree to which I've attached my results. I didn't go through ACOM for my DNA testing but my tree is, apparently, thrown into the matching process along with ACOM-testing trees. I received a message from another ACOM member which informed me we were a DNA "match". I responded to the inquiry by letting the person know that my test was done through another company and provided information about my family line involved in my test results. I received a reply, which thanked me for my response, but my family was, evidently, not a match to her.
I think what you're looking for is instant gratification. Many other genealogists would like that, too. However, family history research takes time, effort, and perseverance to solve mysteries. Private trees on ACOM aren't that difficult an obstacle to overcome in the grand scheme of things. DNA testing won't be very helpful if connected to a poorly documented tree. "Public" and "private" are merely labels as to status and don't serve as indicators of reliability in regards to the information the trees contain.