Kulaks were a class of bourgeois farmers that employed slave-like labor. Dekulakization was the process of ending that slave-like mode of production. I don't imagine you refer to the American Civil War as "Lincoln murdering millions of his own people," do you? Stalin was elected, and did not have absolute power. The socialist system in the USSR required collective decision making, and could not have been run or dominated by a single person, no matter how influential said person may be.