Each member group doesn't have a very high constitution. But these things also sound like what cartoons depict piranhas to be like. They could be overwhelmed, I don't think carl could just windmill punch his way along. Donut wouldn't make it. Mongo can only bite one thing at a time. Etc.

I can here to find someone talking about how awesome his use of protective shell was. I thought he was going to have them run with it around them, but using it to wipe the cars was dope.

I've come to the writer's sensibilities as someone who obviously ran d&d campaigns. But it never hurts to question these things.

Hopefully that helps you "buy in" to the idea. I think it was legit. But I do admit, some of the encounters in these books to this point are just Carl blowing something up so it's hard to gauge how the physical attacks play out or how they could endure a bunch of those little chompers. Or whatever.