[UNANSWERED]The first rule of the blocks' club

Question

You mustn't ever tell anybody about the blocks' club.
What exactly I am talking about is variable declaration inside blocks. For example, if I declare a variable inside for loop, it won't be accessible outside the loop. The same applies for try-catch blocks and other, as I have understood from frequent errors.
Any material on that?
Why is it so and is it inevitable practice to declare a variable outside the block, passing it to the block and afterwards accessing it outside?

Answer 1

what happens in the blocks' club,

stays in the blocks' club

Answer 2

this is probably the funniest post and reply i have seen on here

Answer 3

@Manual
That must be very funny indeed, but I need some helping material.