This is a security matter as well. Imagine a banking site that uses GET to accept input data - apart from the fact that this is incorrect type of call this also lessens security because all your banking activity is left in your browser history. Most often GET data is logged while POST data is not - of course there is no guarantee that a web browser will not log POST data (for example, with an extension) but it is an important ingredient of securing your banking activity and making sure that as little trace is left behind as possible. This is important for any other activities so that your posted messages, sent emails via webmail, online forms, etc. are not left in your browser history, your ISP server logs, proxy logs, etc. indefinitely for everyone to see.