That's practically saying that their main weakness is dealing with about half of the common competitive lists.Their big weakness is 3-agility ships, which is partially where the Thunderstruck variant of that list came from (4x AC Tempest with Cluster Missiles).
Empire: pretty much everything flown competitively but Palp shuttle and Decimators has 3 dice.
Scum: only 2 really competitive lists, Brobots and 4 TLTs, one of them has 3 dice on all ships.
Rebels: here it's getting better for AC Tempests. Corran has 3 dice, A-wings have 3 dice, Poe has almost 3 dice, but then you have k-wings, Y-Wings, Dash and even Fat Han.
Still, a ship that struggles with 3 green dice enemies will have difficulties to be competitive IMO, even without TLTs. Hell, probably even more so without TLT, as a fair bit of the 1 agility ships would be gone too.
True. 2-dice attacks versus 3-dice defenses - especially from lower PS - rarely ends well. Hence the Cluster Missile concept.
A list of pure AC Tempests was never a super-awesome idea, anyway. They should have been the kind of ship that you could mix in as a solid blocker who was hard to kill and had mediocre offense you could rely on. They may yet get back to that point, but it's hard to imagine now.
Tbh, I don't think TLT killed the 1 AC Tempest in a list idea, but rather the multitude of TIE/fo (and TIE/ln) pocket aces. A Tempest starts at 21 points. So does Omega Leader.
But he's loaded out to 26 typically. It's a contributing factor, but I think people played it a few times against Soontir and realized that 2 dice, even when they're always 2 hits have a ton of trouble punching through Aces.
In the ~20 point range I'd rather have an AC Tempest than the 12 PS guy or the 2 distance barrel roll guy or naked Zeta Leader. I'd rather have an Autothruster Alpha than a 20 point FO.