I didn't have this problem with El Capitan, but ever since I upgraded my 2011 MPB to Sierra, I've had problems with blurred screens/fonts. It's driving me nuts. If I log off, the problem briefly goes away and then returns.
I should mention that I do not have a Retina screen and use 1280x800 screen resolution.
I should mention that I do not have a Retina screen and use 1280x800 screen resolution.