Summary: Use role="application" very sparingly, if at all.
NEVER use role="application" on a widely containing element such as <body> if your page consists mostly of traditional widgets or page elements such as links that the user does not have to interact with in focus mode. Using role="application" unnecessarily can cause huge headaches for any assistive technology user trying to use your site/application. Only put it on the <body> element if your page consists solely of a widget or set of widgets that all need the focus mode[^focusmode] to be turned on.
Do Use
- Use if your page has no resemblance to a classic document in roughly over 90% of its content
- Use clear labels within your application