Yes, you can't criticize that somebody made a big library - you have no idea why, how and under what circumstances it was made. Even if the only reason is that the author doesn't find it fun to maintain a bunch of libraries, that's still a valid reason. It's actually exactly that most of the time - it's a hobby, not a job to them. They probably maintain few dozen microservices at work, why bring it home too? In other cases you have resource constraints, cost/benefit optimization, etc.

You can say you'd prefer a bunch of smaller more focused libraries, but criticizing that big one is wrong, especially if you got it for free including the source and a license to distribute and modify it. And this has nothing to do with how you should or should not code, there's no definite way how everyone should code; some prefer batteries-included frameworks and some prefer small focused pieces - it's an opinion more than a fact that small library is better. But even if not, people are free to share their bad work and you are free to pass on it, provide suggestions or patches - but criticizing it is entitled.

BTW it's funny to argue that you should be able to criticize a big library for being too big right under a discussion about dependency version requirement hell. One big library that includes everything would alleviate that pain - perhaps that's what the authors were looking to fix. As I said, this is an opinion, not fact.