Umm, 2 Regional winners would disagree with that. Interceptors are fine.
+1 they're fine, just don't run too many.
We saw virtually no Alphas in the Store Championships, and now we have seen two winners in the Regionals with the same mixed squint squad, which is a complete reversal. But two weeks into the Regionals is too early to make any sort of definitive statement on the meta game suddenly changing.
On the theory side, Alphas still don't make as good jousters as Academy Pilots, they simply cost too much. Interceptors have always been on the edge of being highly competitive, but they are not quite there. However, if you can squeeze three squints into a 6-ship list then you are spending almost all your points on ships rather than upgrades, which is optimal. (96 points on ships for 6 mixed TIEs vs 90 points on ships in a 7 TIE swarm). The added firepower helps offset the loss of having an extra ship plus the extra 6 available points. It also depends on the meta: this particular squad is a pure PS1 squad (minus Howlrunner) so it doesn't waste any points on the PS bid. If your opponent goes all PS6+ then this works heavily in your favor.
As I mentioned in the Regionals thread, I actually played several mock-games with this exact squad when wave 2 came out. It's good but has more weaknesses than the standard 7 TIE swarm.
Regional winners are also a very small sample size of what makes a good list. Plenty of lists are good competitively and didn't win.