Right wing people tend to be subservient and just fall in line and vote Republican. People on the left tend to be less pragmatic and can be enticed to vote for Green or whatever even when it’s obvious they won’t win “because of my principles!” Someone voting Green or whatever will be very likely to choose the Democrat candidate down the list of choice before the GOP candidate. When the votes are tallied they will end up with more votes with a ranked choice system than they’d have with the current system.
The real reason why this won’t happen is if the GOP have a majority since it is very much against their interests.