Not at all! Discourse is a highly sophisticated PWA with a high level of client side UI processing and app-like back-end data frugality.
With support on Android and incoming increasing support for PWAs on iOS together with improvements to push notifications in that architecture I’d say native apps are a lot of effort to go to with increasingly limited benefits.
Indeed the PWA format allows for extension and customisation by Theme Component and Plugins that would not be possible with an app implementation.