Wait, wasn't ultimate alchemy done after tadpole was bred (with ecto-labs) and it is, essentially, heating it, releasing it into core of Skaia and then have it fed all the grist hoards as opposing to mashing captcha codes and spending grist as platonical material?

It is, but my thinking is, if you need to have all that Grist poured into Skaia to get Tadpole from Tadpole to Frog, directly alchemizing Billious Slick would arguably cost the same amount of Grist, if not more. When you’re at the point of defeating the Denizens and the Black King and Queen, warping a few frogs and hunting them down in the planet becomes an utterly minor nuisance in comparison, may as well just poke a frog.