Not to mention that any plant, no matter how many cards or turns the plant player pushed into it (example being Fertilizer), can be shut down with a simple deadly zombie or a destroying/resetting trick (Trampoline, Rocket Science, Weed Spray, Locust Swarm). Depending on what cards are drawn for each turn, both sides have a chance to look OP given the randomness of the cards you draw(you could draw several weak combos while the opponent can draw a huge combo that can wreck you at some random point)
In the pictures you took, the zombie hero seems to have had some pretty bad draws while you got good ones. The Smash could have had a Rolling Stone, Locust swarm, Weed Spray, or other debuffers in the beginning of the match to deal with a growing Double Mint, but he didn't. In the mean time, the plant hero was able to buff up Double Mint and guaranteed a win as the Smash kept earning not so great cards to deal with the current situation.
However, the Smash could win other rounds against even the same plant hero if luck is on their side. For example, say Captain Combustible drew a Double Mint and placed it with a little boost. But unluckily for him, the Smash has a Locust Swarm and a Rolling Stone or two. The Smash lets Combustible build up a Double Mint with tons of cards (Fertilizer, Embiggen, Plant Food) and eventually ends up losing lots of cards to keep it alive. Smash uses a single card, and then he has a HUGE card advantage.
While some cards seem WAY too strong by themselves with nothing to counter them, there are equal amounts of OP cards on both sides depending on the luck of your situation.
