Blinkers

Why did car makers, put blinkers/turn signals on cars? Its such a crazy thing.. Like it only lets the people behind you, or in front of you know what your plans are.. They are so easy to use.. all you have to do is flip it up to turn right.. or down to go left.. gosh.. I guess it really is hard to do isnt it.. I'm gonna start to be like all the people from Pennsylvania and just not use mine anymore.. I'm gonna become a mind read which I guess they are.. You people are awesome.