The Punisher is indeed awesome, but the last two editions prioritized mortal wounds and handed out 4 invuls, damage reduction, and FNPs like candy while also increasing toughness of a lot of units so high volume of high strength -1 AP and flat 3 damage (or spiking damage from a Lascannon or Melta) was essential for being remotely competitive. The Gatling cannon literally was gated via strength to dropping a bunch of shots that you didn't have that many to start.
It's similar to my main quibble with a Vanquisher, I love the dumb tank, it's got a great gun profile if you buff and support the bad BS. I was fighting into my son playing Necrons, and anything big and bad had 4 invuls. I was buffed to a 3 BS via take aim, reroll 1s from Grizzled, I could miss only 17.5% of the time if I rolled a 2. I hit like 5-6 times from two tanks across 3 turns, and only once got through his invul for damage due to a 50/50 chance he could just say 'No' to S18 AP -4 damage 7-12. My Hydra actually did more damage due to FLY on the Doomday Ark, and the Rogal Dorn only did work due to the Meltas that spiked through and some lucky Oppressor rolls... I found myself wishing I'd taken just the battlecannon version as the gun would have done a whole lot more work.