Add that to the erratic behavior that AJAX causes with anything less than optimal network connectivity, and you have a recipe for an unusable web page. Do I need to click on that widget or not? One click or two? Does its color indicate it active, or disabled? Did the click I made register, or did AJAX make it vanish due to network flakiness? Or is the response just delayed? Oh, it did something! Was that my first click (with an unwanted second response coming when the network catches up), or my second one? And so on, and so forth.