"Just syntactic sugar"
That's what most modern programming languages provide. Syntax matters. Kotlin offers a lot of syntactic sugar for things that are a bit verbose in Java.
The new structured concurrency stuff in Java is actually a great example of that. More or less does the same thing, Kotlin manages to do it with a nice Kotlin DSL. Java does it with a lot of builders and function chaining. Which is a lot less readable.
In the end, Java caught up and you can now use this for more complex concurrent/parallel code (both should be possible with this, like it is with co-routines in Kotlin). Which is a good thing.