Epistemology is the philosophy of knowledge. One of its core ideas is fallibility: Mistakes are common.
Problems and mistakes do harm, but can be solved by finding solutions. That's a matter of knowledge.
Creating knowledge focuses on creating good explanations. Since criticism is a type of explanation, it's included. We get good explanations by taking whatever explanations we can think of and improving them. Improving them requires creating criticisms.
Since creating good explanations takes criticism, and criticism is a type of explanation, that means we need to use criticism in the process of creating criticisms. That might sound circular, but it's not because each time we create criticism it's for a different issue. First we try to explain a flaw in communism, say. Then we want that to be a really good explanation, so we criticize any part of it that's unclear. And for one part, we get into a discussion about whether it really is unclear or not. So there's different levels of criticism used.
The whole process can be thought of as the challenge of fallibility. Although mistakes are inevitable, we can make fewer and fix some existing mistakes. Our best tool in this challenge is criticism.
By fixing mistakes, solving problems, and creating knowledge — which are all the same thing — we learn and improve.