>It's complicated

It takes a few minutes to explain to people, but ranked choice voting solves the demonstrated problem of the spoiler effect. This justifies the ever so slight increase in complexity. If the average American voter cannot rank their favorite three things from most favorite to least favorite, democracy is in trouble.

For example, if someone had preferred Ross Perot back in the day but would have chosen George H.W. Bush over Bill Clinton, then Bush would have won, not Clinton, which reflected the majority of the people's will back then.

>encourages back room deals between "opposing" candidates

I'm not sure what you mean by this. Please explain how you think ranked choice voting incentivises collusion.

>hard to tabulate

I could write a program to implement the basics of ranked choice voting, instant runoff voting in a day of work. Over 99% of ballots today are counted electronically so don't worry about hand counted ballots. Also, ranked choice voting can save money in the voting process by avoiding the need for runoff elections.

>encourages gamesmanship by voting blocks

Again not sure what you mean or why this would be encouraged by ranked choice voting more than first-past-the-post.

>enables more fringe candidates to win elections

On the contrary, ranked choice voting incentivizes politicians to have more mainstream policies. Getting people's first vote would be the ideal for a candidate, but if they can get the voters' second or third votes where other candidates cannot, that can win the election for the candidate. So the candidate is incentivized to find common ground with voters who wouldn't have voted for them otherwise.

>easy to corrupt it

I don't see how, please explain.

The only organized opposition to ranked choice voting that I have seen is by politicians who have only gotten into power because people held their nose and voted for them. Ranked choice voting is a threat to their power and their careers because it forces political candidates to reflect the will of the people.