I'm not saying you are wrong. Of course you can use the numbers of renders as indicator for something. At the same time you can compare them with other devs as many people do it. But ask yourself: Are NLT's renders comparable with P&P? In absolute numbers yes. But as soon as you look into the details such as render machine, render technique, render software, you will have a different result.
To continue the NLT example, you will see that NLT use a different software (3dsMax) and not Daz (P&P). NLT also use overlays instead "hard-renderd" images. Means, he use one image and puts different overlays on them to make them appear different (e.g. hair, mouth movement etc.). In case of DrPinkCake most of his renders are frontal shots and he doesn't postwork (photoshop) all of his renders. There are many mistakes in his renders (wrong light, colors, posing etc.) too. Not everyone notice them, because the not noticeable for noobs other artist can spot them right away.
Even if you compare the absolute numbers of renders between devs you can't really tell Dev A is better than Dev B. Because the result is your personal preference and not based on a standardized measurement board.