You all have to learn not to play cards because you can... You also need to learn that some decks are counters to others. You're not going to win every game.
Can it wipe a board? Sure, if you play cards just to fill the board before turn 3. You sometimes have to bait the card. If on turn 3 you have two under 2 damage minions on the board and they pass their minion phase... DON'T PLAY ANOTHER SUB 2 MINION! Either a) they'll get rid of just a couple leaving you with plenty of cards to recover, or b) they'll hold off on using it, wasting a turn.
Another thing to remember, you don't balance competitive games to the weakest decks, you balance then to the strongest.
I'm an exclusively plant player... Just under 50... Still climbing. While i may seem smug, it gets tiring telling people to change their decks and strategies to match the game, not change the game to match their strategies.
Weed spray is certainly not op. If you're going to play all sub 2 damage cards and fill your lanes, knowing the card is out there, is it weed sprays fault or yours if it wipes you out?