Line spacing too large on a hidpi display

I recently switched to a 3200x1800 display and Windows 10, running with 225% scaling. I noticed that the minimum settable line spacing (1.2) is too large:

Is there any reason that line spacing cannot be effectively set to less than 1.2? (setting it to 1.0 seems to have no effect...). Checked on Consolas and Source Code Pro. I'm on Idea 2016.2.1 EAP.