The best technologies disappear into the environment to minimize distraction from the content or experience at hand. Yet we design for distraction, and we call it engagement. When you say "engagement," I now hear "theft of attention."
Designers often conflate device context with user context—or worse, with user intent. “This is mobile, so they’ll never want to do that.” ”This is mobile, so it’s aimed only at users on the go.” Friends, this is hooey.