Because software these days is crazy complicated. You would expect lots of features from any web app that you visit : - Autocomplete for most used items ( emai

Because software these days is crazy complicated. You would expect lots of features from any web app that you visit : - Autocomplete for most used items ( emails, users, etc. ) - Some real time tagging / categorising feature - Confirmation blockers on dangerous actions - Undo button for almost any action - Fine-grain privacy related functionality - Text editor with features, which renders whatever you type nicely formatted - Tons of helpers, video playback functionality, photo gallery, photo uploads, etc. - All of the above free and because of that, tons of analytics included in the page, which show you a relevant advertisement. Yeah if you don't like all this you can replace Gmail with Mac's mail app or any other program that sends / reads mails. You can also replace facebook website with the app on your phone. But you can't have all those features run fast on slow computers and a slow computer for me these days is something < 16GB RAM or < i7.