I think it's far too unimportant an issue to be so terribly dogmatic.
If someone else is using explicit return, it doesn't affect you. If you don't want it in your projects, just ban it in a style guide, or require the use of rustfmt. If someone else wants it used in their project, and you're contributing to it, just deal with it--it won't kill you.
By all means, recommend it and promote it if you want, but there's no benefit to haranguing people.
Unless they use three spaces for indentation. Those people need to be relentlessly mocked and publicly harassed until they see sense and use five spaces like all proper, civilised people do. Damn barbarians...