When you are using the Windows operating systems, every line is terminated with a CR and a LF (ASCII values 13 and 10). Windows stores files as ASCII - 1 byte per character. So every line takes up at least two bytes. Blank lines take up exactly two bytes.
Line's are terminated with a LF on UNIX systems and CR on Mac systems, thus one byte per blank line.
Yes, the style guide sucks up more memory than the popular styles of ten, twenty, thrity years ago (damn, I'm so old!). But back then, storage space (
cards, paper tape, etc) was much more precious than it is now. Now, readability and ease of use is far more important.
Java does take up twice as much space for every character, but it you write your files out to an ASCII text file, it goes back to one byte per character.