Redux is a bit like Java: it's possible to write well-designed software with it, but it's also gotten a reputation for being used by the sort of programmers who blindly apply "best practices" and create nine layers of AbstractFactoryGeneratorBeans for everything.
I suspect one factor in this is that if you know enough to apply Redux's patterns well, you probably also know enough to implement them yourself without bringing in a third-party NPM package. (Of course, not everyone will choose to do this --- maybe you like the Redux debugger UI or something --- but I think enough people do that it lowers the perceived average quality of codebases that do use Redux.) The library just doesn't do anything difficult in the way that, say, React's virtual-DOM diffing and reconciliation algorithms are difficult.
I suspect one factor in this is that if you know enough to apply Redux's patterns well, you probably also know enough to implement them yourself without bringing in a third-party NPM package. (Of course, not everyone will choose to do this --- maybe you like the Redux debugger UI or something --- but I think enough people do that it lowers the perceived average quality of codebases that do use Redux.) The library just doesn't do anything difficult in the way that, say, React's virtual-DOM diffing and reconciliation algorithms are difficult.