It's a shortcut for "early-returning" in error cases

> Was more boilerplate necessary in the example before?

Somewhat yes, the original use case is Result types (and the try! macro):

    let v = func()?;

expands to

    let v = match func() {
        Ok(v) => v,
        Err(e) => return Err(From::from(e))
    };

that is it "unwraps" a successful result, and barring one it directly returns from the current function (having possibly converted the error). Before 1.22, doing that with an Option would be:

    let v = match func() {
        Some(v) => v,
        None => return None
    };

or

    let v = if let Some(v) { v } else { return None };

after 1.22, this becomes

    let v = func()?;

as well.

edit: note that this is quite different from the behaviour of the ? operator in languages like C# or Swift where it compounds into "null-safe" operators, the most famous being the null-safe navigation operator "?."[0], these are closer to the monadic bind, which in Rust is called "and_then".

[0] https://en.wikipedia.org/wiki/Safe_navigation_operator