The cynical answer is that it's too easy to play, too good, and has been insanely popular for very long. People always shit on the most popular strong deck.

I think the underlying issue is that it has this weird combination of both being too consistent and too RNG/high-rolly.

The consistency is absurd. There are so many 1- and 2- mana pirates that generate more pirates, or give you a 1/3 weapon, or let you draw a pirate, etc. meaning you never have to play a bad, or even mediocre, card.

The idea behind a quest or questline is supposed to be "here's a deckbuilding limitation. You will have to sacrifice to meet that limitation, but the payoff will be worth it."

Except pirate warrior doesn't have any meaningful limitations. Each card is pretty darn good. So every single game (every. single. game.) the deck will consistently roll out a bunch of good cheap drops which lets them tutor the best card in the deck (Ancharr) on turn 2-3.

Being able to tutor the best card in your deck, every game, in the first few turns is an insane amount of consistency in a CCG.

That card then lets the deck draw more, getting rid of the biggest weakness you're supposed to cope with when playing an aggro deck: managing fast but limited resources and deciding how wide to go so you don't run out of gas.

Then there's the RNG part of it.

The "do 2 random damage" comes from six different cards in the deck (Cannoneer x 2, Ship's Cannon x 2, Quest Step 2, Juggernaut) and I've lost count of how many times I lost because those two shots hit exactly what they needed to hit to give my opponent the win.

Like even if I have a fairly wide board, and all that fucker needed to do was get past my one taunt minion, and wouldn't you know it?! Both fucking hits pinged the one taunt minion, letting him SMORC for the win. Losing on that kind of randomness feels really really bad. And it happens constantly against pirate warrior. So what happens? People come to reddit and rage about it.