What is the point of the location of the files above www?

Question

PHP

I have seen more than once that in web applications they put system files above www. But after all, when you go to ftp, you can see this folder there and you can go into it, upload something.
Or is it not for the case when the FTP password is stolen? Then against what?
And what to leave in www then? Only index.php pictures, styles scripts?

Answer 1

The point is that in www (and only there) the web server has access. Accordingly, everything that should not be available to the web server (for example, source codes, configuration files, etc.) is placed outside this folder. This allows you to protect yourself from the web server configuration curve when it starts to give the source as text files, for example.

Answer 2

boldly put everything in www, all these horror stories are sucked out of your finger