Oh yeah, already encountered Double Ball (unfortunately). There was a dryad-spamming guy who was equally stupid. These decks are in the meta atm?Yes, there would be no way around it if the faction in question didn't have an alternative. The thing is, there's at least two decently powerful and then many more meme-ish-yet-kinda-decent Nilfgaard decks that don't involve poison/Vincent Van Murlegem.
You'll understand soon enough.
Short version is - nobody likes it when an enemy deck can kill everything on your side of the board, and unfortunately this is exactly what's happening with Nilfgaard right now. A lot of people had to switch to decks that counter poison mechanic specifically.
(Expect a lot of voiced trying to disprove what I've just said. If you want to build your own impressions, try searching "Double Ball" here on forums and allocate some time for reading of the relevant threads)