You can still do that, but 1) much better email lists exist that the RNC was already sharing with the Trump campaign, 2) algorithmic targeting almost always beats uploaded lists nationally anyway.
I assumed email lists of people who'd taken the personality tests, then maybe LAL off the back of that. How was the algorithmic targeting back then? I know I wouldn't want to manually optimise against it now (with the right spend).
Just to caveat again - not my specialty, but very interesting all the same!
It's even better now, but in 2016 it was still really good. in 2016 I was using FB targeting to find business owners who were in the market for loans, which is far more specific than democrat, independent, or republican!
Admittedly I based a bunch of this on Alexander Nix's utterly fascinating OMR presentation (https://youtu.be/6bG5ps5KdDo). As per the parent, it always amazes me at how easy it is to influence someone if you know the right levers to pull.