To make this argument carry more weight, here are the facts, similar to what was provided for Mad Dog spam:
This is a problem because for only 12 points, the army gets nine models. Unassisted, they threat 16" and so do not have to be exposed until they need to attack. Destroying them preemptively takes considerable resources, especially considering they are DEF 13 with Force Barrier. They can be in formation for Triangulation quite trivially. Their attacks become high RAT (8) and natively ignore the three most common defenses against ranged attacks (concealment, cover, and stealth). These attacks become a respectable, but not absurd, POW 12. With relatively little positioning, and minimal advanced planning in army composition, those attacks can be POW 14 for multiple rounds and POW16 for one round. There will be 27 of those attacks, which is likely more attacks than some entire armies can bring to bear in a round. These attacks will be effective at: 1) putting serious damage on hard targets, 2) eliminating swaths of light targets, and/or 3) assassinating leader models. They also are magical (bypassing some additional defenses) and have critical disruption. Nothing in the game brings so much for so little with so few options to avoid it.
This game is not in the same place as it was in 2016, so the ultra-competitive players will not be making waves as fast as they did in the past. People seem very excited by the new armies, supply of older models is limited, and powerful things are not always instantly adopted. How long did Body and Soul or Ghost Fleet exist, with all the pieces available, before players realized, and brought to bear, their power? Just pointing out that this hasn’t torn up the competitive scene isn’t justification for ignoring it. Preventative measures, when a problem is clear, are healthier than reactive measures.
What we have here is far from panic and theory, and treating the arguments made so far as such is pretty dismissive. Many of us have been with the game long enough to know the cycles that happen. It is our experience that explains precisely why why this concern is being raised now. For 12 points, you easily get 27 high-quality attacks. It’s beyond the power curve, not just a new thing for players to adjust to (re: Eiryiss or shield guards).
Yes, there will always be a “strongest” thing in the game, but that doesn’t mean it has to be ludicrously strong. If we’re looking for quantification of “power,” which is difficult, I’d be curious to see what people think comes closest to the power of Stormsmiths. If they’re just a bit better than other things near the top of the curve, that’s fine. However, I think this is a curve with a long tail, indicating a skewed distribution of power, requiring attention.