It was a satire of the attitude of American society towards communism during the cold war. The equality-by-outcome it presents is a strawman, precisely the strawman attributed by conservative politics to people who want to make society more equitable not just in "opportunity" but "outcome" as well. Vonnegut was a socialist and was quite warm to concepts such as "from each according to his ability, to each according to his need".

It's really hard to see how people miss this subtext when the main character of the story declares himself the emperor that all must obey and defies gravity. It's so cartoonishly heavy handed!