Because the job is rarely just manipulating the Dom in some simple way. Sure, if you just want to add the current date to <div id="rightNow"> then use basic br

Because the job is rarely just manipulating the Dom in some simple way. Sure, if you just want to add the current date to <div id="rightNow"> then use basic browser builtins, but it's usually more like "I need every other child of each list with the class 'rowStripe' unless it's the last entry in the list", in which case jquery saves you a ton of time.