Responsive sites have to be like elastic 'jelly' and accommodate every view-port resolution. The only exception being non-mobile-friendly web apps, in which case some sort of manifest should be read by the browser and presented to the user clearly stating mobile isn't supported and they should use a desktop browser instead.

Then there's the progressive web app (PWA) debacle, where users don't even know what a PWA is and don't know that they can pin sites to their home-screen, simulating an app.