[Fezzik]

It became necessary because, for years (decades), if you made a comment online that your personal experience informed you in such-and-such a way, the first comment would always be some moronic comment dismissing that personal experience because it is just one person’s experience. So, to avoid that idiocy, people started to preface their anecdotes by acknowledging that they know it is an anecdote. It sets the tone for the conversation.

[davebren]

Yeah but we can't let the insufferable dictate our way of speaking. In spoken language I hear it mainly by people that don't have a scientific background trying to sound more scientific.