There are multiple ways to interpret what you said.

If one state uses RCV only for their primaries, then they could do something like vote for Sanders - let’s say that e.g. 42% of votes do that - but then unless Sanders got the top vote, redistribute all of the votes that would have gone to him to someone else. So if, say, Biden got 45% of votes, then Biden now wins, but still there was value in allowing people to vote for Sanders who otherwise would have been too afraid that a vote for him would have split the vote away from Biden and towards some crazy candidate instead. Also, being able to see those stats can be really helpful for the next election, if Sanders were to run again, or even for the current one to let Biden know that he should perhaps adjust his stance to court those other voters.

But the above is to use it purely for the primaries, and yet RCV could also be applied to the general election too. Although really, what need do you even have for a primary anymore, since you could just use RCV straight from the start? If the Dem vs. Repub voters are split 50/50, then 42/2=21% of voters picked Sanders, and 22.5% picked Biden, yet with the latter as the 2nd choice on all votes for the former, Biden would get rather 43.5% of the vote overall, and the same with the other Dem candidates, and similarly on the other side as well.

RCV is all about increasing choice. According to the devil’s advocate argument you put forth:

wouldn’t progressive states using progressive voting systems water down their chances versus republican states who would not have them?

No, b/c Biden would still get all 43.5% of the votes that he would have before. So according to this, nothing would be lost?

Although that ignores what would happen if people were not divided solely into two camps: if a bunch of Dem voters picked Sanders as their first choice, and a bunch of Repub ones did the same, then that is where something could get “lost” - Biden in that case could have lost to Sanders!! In that case, yes something gets “lost”, but that is the very intent of the design, to allow voters to choose such a scenario in the first place!?!?

Whatever the people want, that’s what they should get. As opposed to right now where you have to make a guess about who you think is more likely to win, regardless of who you want. No matter how you slice it, RCV increases choice.

With one exception, which I mentioned: if a progressive state gives up their vote to whatever the will of the country is overall, then they lose some of their power. However, (a) the candidate would have to win the popular vote - which in some sense means then that they should deserve that vote?; (b) lately liberals always win the popular vote, so it is not much of a risk. But it is an - admittedly odd - way to go about setting up a RCV-like system, where a state could e.g. vote for Sanders, but then if Biden overall won the popular vote, then switch it over to him. So there, people still end up not having to play that “guessing game” where they pick whoever they think can win, b/c with that fallback mode engaged, they can afford to be more risky, and e.g. vote for Sanders. Again, the risk would be if Trump somehow won the popular vote instead but… that seems extremely unlikely, and yet if he did, then wouldn’t he “deserve” that vote? Yeah this one is a bit round-about and backwards, but it does work towards the same goal… if I am understanding it correctly, which I may not?