Why Web Installers are great

Are you one of those who is wondering why all of a sudden every software has a Web Installer (a small executable that downloads rest of the stuff) instead of a traditional setup.exe which used to the sole file you needed to install a software? The reason is, a web installer is a smart tool that assess how many components are already installed, and based on that downloads only the stuff that you actually need. This reduces download size from say 500 MB to just 100 MB if you already have most of the dependencies installed.

(I knew this for a while but recently happened to program one such installer and was admiring the beauty of this simple idea)