Ever played Loggy Acres vs 5 Chompers while carrying a bomb? with no engineers in your team? Good luck winning!
*I'm only talking about Turf Takeover final objectives for now*
I think that one of the reasons the success rate for the plants is really high on Loggy Acres is because of Chompers trapping every corner and burrowing most of the time since they know where the bomb is coming from. It's an infuriating experience with zero gun play. I'm supposed to rely on my teammates but will they really try to counter those Chompers? It rarely happens.
On the other hand, the success rate seems higher for plants too in Turning Point (getting batteries) I'd say out of 10 games, 6 or 7 games are usually won by plants in there (the plants team must be really bad if they couldn't win this). Let's imagine that the zombies had a Chomper as a teammate in the same exact map, do you think the plants would manage to escape with batteries? as soon as those Chompers see where the batteries are, they will burrow towards them and insta-kill them. Just like Loggy Acres.
Yes, you can avoid a Chomper if you're 1v1ing them in normal situations and most zombies can find a way to deal with it. It still makes it difficult for the zombies to do their roles (e.g. a Chomper that always kills Scientists or key players during contesting phases. Super Brainz may not be able to do the same thing to the enemy Sunflower because she can always overheal herself (after she unlocks those upgrades). And then she might just get "revived" by others while Super Brainz die in the process.).
*Disclaimer: I'm talking about games that have more than 2 Chompers. 1~2 Chompers are usually fine. Unless they're both really good.