If a solution doesn’t have a realistic path to implementation, it doesn’t matter. The system itself is designed against change, RCV is something neither party actually wants.
Some few Democrats or states are allowed to support it as far as it gives RCV supporters some semblence of power, without actually pressuring the system.
Even if RCV was implemented, and a Third Party candidate won, the 2 establishment parties would work against any radical change.
It pressures the system in those cities or states, which is actual pressure to the system, just not direct pressure on the federal government. History shows you can mount pressure through local and state changes until it gets overwhelming support on a federal level.
You can make the argument there might be more effective or quicker solutions, but this is unquestionably one path toward it.
My point is that tiny, inconsequential pressure is allowed so that you think it applies pressure. Whenever it gets close to making a difference, it won’t.
You say that with a lot of certainty, but without any evidence to back it up. If history is any indication, lasting change is won from the bottom-up. You have to get the masses at large on your side first and the best way to do it is to show them, in small steps, that it can be done and that it’s effective.