I've been looking at job listings, as a starting place on what things I need to learn, and one of the things I noticed was listings for web developer positions that require experience with/knowledge of MVC and Single Page Application frameworks like Angular or React. I'm somewhat confused because from what I've learned so far, SPAs take care of lots of the server side functions on the client side. Is it commonplace to have MVC applications that also use SPA client side functions with Angular or React?

Edit: it's probably pretty obvious but I don't know much about angular or react.