This is a myth, unfortunately. The form of RCV used in the US does not make it safe to vote for the candidates you actually like; you still need to take electability into account and vote strategically to avoid wasting your vote. Other ranked voting systems *do* actually fix these problems.

#RCV doesn't ensure that the winner is supported by a true majority, either. It just eliminates candidates based on an incomplete count of voter preferences until it has created the illusion of majority support.

#RankedChoiceVoting can elect candidates who are not supported by the majority, too, since it eliminates candidates based on incomplete information about voter preferences.

#RankedChoiceVoting is incapable of finding the true majority winner because it doesn't actually count all of the rankings that voters express on their ballots.

#RankedChoiceVoting doesn't prevent spoiler candidates, and is incapable of finding which leaders are supported by the majority, since it doesn't count all of the voters' preferences. A candidate can be preferred by supermajorities over all others and still be eliminated under RCV.

#RankedChoiceVoting doesn't actually fix the spoiler effect, though. It eliminates candidates using the same 1st-choice ranking tally that we have now.