i played UWx legacy stoneblade for
years and feel like I can say a few authoritative things about stoneforge/batterskull together. even by the mid 2010's in legacy 'cheating out a batterskull' was not very good; you tutored for batterskull in matchups where the ability to 'gate' the equipment (and then return it to play with stack trickery) was about as important as the 4/4 lifelinker was. against creature decks I definitely preferred Jitte, to present an on-board lock, not for the 'skull to sit around vigilantly blocking and gaining life.
i won't lie to anyone that stoneforge mystic is an unplayable threat, that it isn't strong to tutor and uncounterably-put-into-play pieces of a toolbox, no matter what that toolbox
is. stoneforge mystic that tutored for
a sorcery and let you cast it for free would be breaking "too many rules" of the game engine. But I think that even if SFM is the strongest threat in your cube at that price point (two mana creature from whom you get more value if you can untap with it), and even if the uncounterability or tutoring are relevant and meaningful in your format, the card is so iconic, so toolbox-y, so
fun to draft, that even with the uncounterable turn 3
Dragonwing Glider or Batterskull play available, the card is so repeatably fun and decision-rich to play with...that I agree with blacksmithy above: let it do the obviously kind of busted thing as well as all the not-so-obvious busted ways it still gets to flirt with the game engine (which Rusje points out).