That's what the digestion upgrades are for. The chomper can completely eat the smaller zombies in only about a second now since they buffed it. And the chomper is far from useless in garden ops (aside against certain bosses) there are many high threat zombies that the chomper can take out of the fight instantly by eating them (people tend to forget about that when using spray chompers i guess). The spray chompers don't struggle aside from chomp thing because he has low health and his spray is weak. same could be said for the toxic chomper but at least he has higher health
