@MontereyJack,
Multiple rounds of voting is not a new system in Iowa. What is new this year is limiting it to two rounds.
Previously in Iowa, people who supported non-viable candidates had many rounds of voting to swap and keep swapping their votes to someone else.
The multiple rounds are not done electronically either. People actually physically walk to whatever cluster of people represents whoever they are going to support in that round. And everyone can talk and debate with each other to try to change each other's minds.
That's why I think a caucus sounds a lot more fun than a primary where you just mark a ballot and go home.