Democrats hugely benefit from FPTP so they will never advocate for replacing it.
Key point, Newsom of California vetoed a bill to enable more ways to vote then just FPTP.
FPTP is in the benefit of both parties. It rallies and polarizes so any other idea besides "Let's not find war, let's fund education and help people" is considered too unpopular to win.
They like the optics of leaving reddit, but like the ability to spew bigotry on flat.world and act like it's their digital 1st amendment rights.