"OK," you ask, "but what about the original idea, that electors can vote their conscience and don't HAVE to follow the popular vote in their state. How does this prevent *that* ?"
Answer -- it doesn't have to. Remember, the states are pushing this are those with (for now) Dem Governors and/or Legislatures, hoping that, if their state DOES vote for Trump, they can get away with voting for Biden or Pocahontas or whatever.
The problem is, for the states already blue enough to give the popular vote to the Dem, they're voting that way anyway.
But for the states who vote Trump for President? Their electors are chosen by the REPUBLICANS in their state, who aren't in on the scatterbrained, treasonous scheme.
Thank you for more explanation. Helps.