The benefits of using the Mobile, Widget, and iPad applications is the ability to track time both online or offline at any point. The applications will store all data until you have an internet connection. Once an internet connection is available, the entries will upload automatically so you will not have to manually sync them over. There is no need to enter your entries on a piece of paper or sticky note to hopefully remember to enter them when you get to a computer with these applications.
Please note that if you are on a Mac using the Chrome application you can still use the application Online & Offline with the Chrome App Launcher: https://chrome.google.com/webstore/launcher