Checkered rendering is not upscaling though. You can't tell me that any upscaled 540 could ever look like this:
Screen is from PS4 version, and I've intentionally picked the one with the most sub-pixel detail I could find where the resolution problems would appear the most visible. 540p uspcaled would look like a muddy pixel soup.
Also, what of the games that use dynamic resolutions? Other than telling you what's the maximum and minimum buffer in that case, there's little information that can be inferred from that, outside of careful scene by scene analysis.