Ticket app not supported on IE8?

I'm curious why the ticket app is not supported on IE8 since this is a supported browser.

Code:

Ext.define('Ticket.controller.Root', {
    extend: 'Ext.app.Controller',
    ...
    onLaunch: function () {
        if (Ext.isIE8) {
            Ext.Msg.alert('Not Supported', 'This example is not supported on Internet Explorer 8. Please use a different browser.');
            return;
        }
        ...