In many cases, yes. But additionally, even with mostly reliable reception people don't want to have to depend on that reception. It's poor form and poor design to include an intermittent service (even if largely reliable for a large portion of your users) as a mandatory component when it is technically unnecessary.
Offline first is simply a more reliable way to build systems than online-only. Specifics long forgotten, but a few years ago (perhaps 10+ now) a lot of people got, understandably, upset when they found out their single player games couldn't be played without an internet connection in order to authenticate. Oops, auth server went down, players can't play the thing they dropped $50+ on.