Just saying, out of my 7 losses this season, 5 have been donks and 1 was a curbstomb game (Blaziken vs Turtwig).
Donks themselves aren't neccesarily bad for the game, if in moderation (Think back to Riolu vs Holon Castform, or Infernape + DRE). But those are all, like I said earlier, SITUATIONAL donks. They happen because you have a lone basic, or because you happen to have weakness. Those happen.
But the donks that we see nowadays are just stupid. The following cards can pull easy donks:
Uxie. Shuppet. Dunsparce (lets not forget about him), Kingdra, Jumpluff, Donphan, Machamp, Sableye. And then there are the more situational donk cards, like Garchomp C, Ambipom G and the works. None of them really care about what they face, they're gonna donk it most likely anyway (Unless you start with, say, Dialga G, and even then Uxie, Shuppet, Dunsparce and Machamp can trololol you all day long, and even Kingdra and Jumpluff can thanks to Belt and Crobat). Thats the whole stupidity of the current state. Back when we had DX/HP On, donks were rare. I can't recall a T1 loss from before LA, when I got faced with T1 Kingdra + Buck + Pluspower.
Had it been just Kingdra, it wouldn't be a huge issue. We've always had speed decks that could demolish stuff early game but would likely falter if a big deck managed to set up (For example DX-On had Banette Ex). But at least those speed decks allowed for a game to be played out...