Promises: Visualize the benefit of async

I'm taking several JavaScript courses, including a course by Jad Joubran.

The chapter I am on is teaching async/await, and how they are syntactic sugar on top of a Promise. Jad's course provides the learner with a sandboxed practice environment.

When pairing async with an arrow function's implicit return, three lines of code can be reduced to a single line, as seen below. Each of the below has the same outcome.

Full Promise

const canVote = age => {
    return new Promise(resolve => {
        resolve(age >= 18);
    });
}

canVote(20).then(result => {
    console.log(result); // true
});

async/await

const canVote = async age => {
    return age >= 18
}

canVote(20).then(result => {
    console.log(result); // true
});

Single line

const canVote = async age => age >= 18;

canVote(20).then(result => {
    console.log(result); // true
});

Granted, this example an oversimplification of an async function, though I can't imagine this doesn't have its uses.

There is of course also the bigger question of "code for the sake of brevity", versus "readable code". [The general consensus seems to be that "brevity === bad".]