Anecdotally, in Japan and SEA we have Line which tries to be an everything and fails everything but the messaging itself because individual components are simply better elsewhere. AFAIK it's losing market to Whatsapp and Telegram pretty badly these days too.
Launching a different app is not that much more difficult than going to a different window within an app. It's almost like we already have everything apps in the form of app stores and web browsers huh!