The ES6 standard comes up with Temporal Dead Zones, making a variable reference not possible in any way until the lexical binding is evaluated. So what does variable creation at the time of lexical environment initialisation mean to
The declaration of a variable using var declaration might mean something to the programmer previously, but now with TDZ in place does javascript start behaving like java for this purpose? Is there any reason other than the way javascript interpreter works that we have hoisting (as a result TDZ) in the first place?
What happens when a lexical binding is encountered later in the code due to order of execution even when the code appears before it lexically?
let abc = f();
let b;
f(){ return b;}
When does traditionally programming languages like java create variables? When the variable declaration is encountered? or when the lexical scope is initialised?
I have a feeling that the creation of TDZ had to do with it being a very menial step from var, whereas if they were to go with the seemingly more logical approach of not even having the identifier exist, the engine would have had to undergo even more intensive changes. As for the second part of your question in reference to when other languages "create" variables, there are many other important factors to consider that you seem to have left out, such as is the language interpreted vs compiled, as well as there are multiple different steps to "creating" a variable. It acts differently in many different cases, and there is no single answer. In fact, that is one of the big reasons why there are many different languages.
As for your coding question, it would depend on when you're calling your f function, since function declarations are hoisted in javascript. If you are calling it before b is declared, then you are in a TDZ and b cannot be referenced. It will behave very similarly as if you were simply putting the return b wherever this function is called.
Honestly, it seems as if there is some underlying misunderstanding of javascript, and computer languages in general. Javascript is not "behaving" more like java, in fact the new let keyword has very nuanced behavior, such as being able to be block scoped, compared to type/variable declarations in java. I would suggest not trying to think of the changes in ES6 in terms of other languages; javascript is not like a lot of other languages, it will be very difficult to understand the concepts and how you should be programming with javascript if you do.
EDIT:
As for why there is variable and function declaration hoisting, that is easily googlable.