Ranked Choice or Instant Runnoff Voting has some serious foundational problems.

The first of which is that it's actually a series of Plurality elections run at the same time. You cannot fix the problems of Plurality by iterating Plurality.

Basically, because Plurality and RCV and such are Ordinal election systems built on the word "Or". You can support A or B, but not both. This is where the spoiler effect comes from, and it leads to extremism.

Cardinal voting systems like Approval and STAR are built around the word "And". You can support A and B at the exact same level, and this means there's no such thing as a spoiler effect.

I've voted in primaries. There are generally two or three solid candidates who I like, and one or two very bad candidates who have a narrow, but dedicated support base.

Under any ordinal voting system, the solid candidates lose, because there were too many of them. Even when most people would have preferred them.

Under a cardinal system, that's not needed. You can give each of the solid candidates full support, and then not care anymore because one of them will likely win.

I agree.