No,
render engines can be compared extremely precisely, if you know what you are doing. Light clamping, etc… will show only if you compare identical setups, which was not the case. It’s highly dependent on the skill of the person doing the comparison. You can’t just compare denoised images and at the same time claim that you even remotely know what you are doing, and then defend that by saying precise comparison is not impossible. It is, you can see it for example here:
Where I first establish some baseline and get at least rudimentary data until I start throwing the denoiser into the mix.