Given that others have reported it, and it's been there for a long time, I suspect Twitter at the very least intentionally doesn't put too much resources behind the web site to force people to use the app.

Of course, if a service really wants to push an app onto me, it's clear that the app gives them some real benefits, and its usually the kind that aren't a benefit for me (more tracking, better ways to push ads, more "engagement" notifications, ...). So the harder something wants to push an app, the clearer it is that I never, ever want their app to touch my device.