Yeah, I just don't get the point of introducing a third category and making it opaque to the mechanics already existing in the game. It's like having arcane magic, divine magic, and psionics: a mage can dispel a divine spell, a cleric can dispel an arcane spell, but for some reason neither of them can do a thing about psionics without significant investment. It's the world designers saying that the new option is not just different but qualitatively better.
If you're just building a PC for Iron Gods, it should be pretty obvious which options will be important: just like you'd put ranks in Swim and Profession (sailor) for Skull & Shackles but not, say, Rise of the Runelords. But for Society play, when you have PCs for whom Technologist has never been an option and it's suddenly near-mandatory, it's changing the rules of the game in midstream. Apparently, the Society people didn't know about the decision to make technology opaque, and the first scenarios of Season 6 have Knowledge and Linguistics and Disable Device checks that are impossible for PCs without the feat even to attempt.
And apparently Fires of Creation lets you attempt a Disable Device check at a -5 penalty without the Technologist feat, which sounds eminently reasonable to me. Once again, the AP line proves its superiority over the "let's hire a half-dozen freelancers to churn out twenty feats, spells, traits, and archetypes stat" line.