Nope. Especially for this reason.
Commenting as non-staff was possible in the past, with a note that it was't a staff reply. However, closing was always reserved for staff. Over time, more and more people did it, but people started to give information based on an incomplete picture. Saying things like "you need to do X and you're good", but they didn't see the user was blocked and thus inegible. Things like that. So when adoptions were delegated to Managers (or shortly thereafter), the practice was stopped.
If someone makes an adoption, they're expected to read the guidelines, follow the steps and have everything filled out. If they can't do that, it's their own time they're wasting.