It's not about peaceful routes, it's about sustainability and avoiding evil.

Not all Bolsheviks were awful, too. It's just that the general agreement about "we are doing a marxist revolution and transforming a country worse than intended for that, and so we can only afford unity and centralism, and some hard solutions are necessary" meant that the hard solutions led from executions of some people to executions of many, and unity led to gradually destroying opposition (the communist kind), and centralism led ultimately to Stalin.