Unless you mean negative voting/voting against, which you only get by introducing a "none of the above" option so that the electorate can vote in such a way that even the most "popular" voted candidate can still lose because of the negative below-"none-of-the-above" votes outnumbering the positive votes - putting someone below "none of the above" in either stars or ranking makes it a vote against them whilst still enabling you to distinguish preferences between candidates who you would prefer were outright rejected even if your candidate can't win.

We should not be trying to “save” RCV

I'm not trying to save RCV. I'm saying star is better for public elections. Twice. At least.