, I agree the call number is essential to a proper citation as you've described.
We wouldn't want to equate this to viewing a US census record in digital image at Ancestry, which adds its own "image number", quite specific to Ancestry.com alone. US researchers bemoan the regrettably poor citations at this website,
After finding a US federal census enumeration in person at our National Archives, we'd have to settle for microfilm copies, only generally referenced in the Ancestry.com citation.
A competent would need to cite the specific roll number, but not a drawer number, because the drawers are labeled with beginning and ending roll number. One would also include page number and household numbers.
Much more to say on this, but as you know I'm at the hospital keeping watch on Mr. Myrt.
Suffice it to say, we cannot judge an appropriate census citation if it appears at Ancestry.com. Good clues are found therein, but full citations require additional components.