For a social media type app that is simply opening some web content, sure. But, as always, you can’t make these categorical statements because there are many instances where an in app browser is essential. For example, needing to access an institutional SSO login page from within an app, or transition to an external payment processor. Or display a hosted PDF document to the user without having to completely leave the app.
There are a multitude of very valid reasons that a web view is useful to the UX. Constantly leaving the app loses context and can make it very difficult for many users to even know what happened or how to resume their intended path.