Why does this need special syntax? Couldn't blocks do this if the expression returns a result in the end?

Try blocks let you encapsulate the early-return behavior of Try-returning operations so that they don't leak through to the surrounding function. This lets you use the ? operator 1. when the Try type doesn't match that of the function this is taking place in 2. when you want to use ? to short circuit, but don't want to return from the enclosing function. For instance, in a function returning Result<T,E>, you could have a try block where you do a bunch of operations with Option and make use of the ? operator, or have ? produce an Err without returning from the enclosing function. Without try blocks, you pretty much need to define a one-off closure or function so that you can isolate the use of ? within its body.

The best part of try blocks is the ability to use the ? operator within them. Any block can return a result, but only function blocks (and try blocks) can propagate an Err with the ? operator.

Not without being able to use the ? operator.

The closest thing I can think of that will let you return a result from within a separate scope using a set of foo()? calls would be a lambda function that's called immediately, but that has its own problems when it comes to moving and it probably doesn't compile to very fast code either. Something like https://play.rust-lang.org/?version=stable&mode=debug&editio...

One reason is that would be a breaking change.