because they realized that the IDEA of Democracy as a rule of majority for the common good was a FARCE. When Castro Overthrew Batista he had tried several times to run for parliamentary seat in Havana but always Batista and his cronies would Block him.
If you look at Zimbabwe, Kenya etc you realize that the IDEA that Democracy is serving COMMON Good is as a Flawed as the government of the day.
There countries out there in this world that Require Less democracy and More of benevolent Dictators.
Kenya is one such country