If you have a worldwide audience, or your site is hosted in a different country from where your visitors live, it is useful to see how long it takes to load your web pages.
Why can't you just use your own browser...? Because they have a better connection? Well, that's not accurate either, because the places that page are going to load are on machines with consumer level connections anyway. Firefox and Chrome are hideously out of date too. It says it has 3.6 and 8, and the current ones are 7.0.1 and 15, respectively.
this is so stupid
Useful tool to test how fast a webpage loads from different locations and in different web browsers.