I think he is guessing that the grandparents thinks that www or 'world wide web' means 'the internet' and should be root.
But actually 'web' reveals to the graph of hyperlinks between http/html pages that let you navigate from page to page, server to server. www denotes the host is primarily a http server serving web pages.
You could argue it's superfluous these days - if you are typing it in an address bar, you hope it is a http server, and if you are typing it in a ssh prompt, you know it's your ssh server. People add it because it's a convention and some users might get confused if you don't... (it's probably a vhost anyway most of the time)
But actually 'web' reveals to the graph of hyperlinks between http/html pages that let you navigate from page to page, server to server. www denotes the host is primarily a http server serving web pages.
You could argue it's superfluous these days - if you are typing it in an address bar, you hope it is a http server, and if you are typing it in a ssh prompt, you know it's your ssh server. People add it because it's a convention and some users might get confused if you don't... (it's probably a vhost anyway most of the time)