It amazes me how much people get hung up on this versus that formula without paying equal attention to how printing papers significantly differ from one another. Even the same VC paper in the same developer can take on slightly different tones depending on the ratio of VC exposing light. Or it can change personality depending on the length of development, combined with post-toning response.
Dektol generally trends an annoying greenish. Cold tone MQ developers have various responses. With Polygrade V, it could be almost a blue-black; with Ilford MG Cooltone, you never get rid of the greenish bias. The only true neutral black I've gotten with Cooltone is with 130 plus toning in gold chloride. With MGWT, the effect is quite different, naturally. And those classic old graded papers? - well, they're all gone anyway.
Quantification has it place; but so does one's own pair of eyes, which is the final arbiter. Final image tone is quite important to me, and I want to be able to finely tailor it to each respective image. I switched to 130 as my primary developer quite awhile back for a reason.
My jar of amidol powder now has a very lonely life; and any remaining packs of Dektol haven't left their storage shelf for decades, not since Seagull G paper disappeared, which had just enough purplish hue to it to offset the green. The subtle gradation of 130 also differs from Dektol. And all along, I've been diluting it 1:3. But admittedly, I'm not someone who saves used dishwater for the next day, or used developer either.
Chemicals aren't just chemicals. There are different grades of purity to them, and different shelf lives. For example, I was told photographic amidol had to be of a higher purity than even medical amidol, by a phD who mainly sold it to pharmaceutical labs. Glycin changes its personality as it ages, until it turns into nothing more than a chocolate stain, really. That's why unopened glycin powder needs to be kept frozen.
