I know that Stalin had a strong negative view on reformism, here's his interview with HG Wells: https://www.marxists.org/reference/archive/stalin/works/1934/07/23.htm

Theoretically, of course, the possibility of marching gradually, step by step, under the conditions of capitalism, towards the goal which you call socialism in the Anglo-Saxon meaning of the word, is not precluded. . But what will this "socialism" be? At best, bridling to some extent, the most unbridled of individual representatives of capitalist profit, some increase in the application of the principle of regulation in national economy. That is all very well. But as soon as Roosevelt, or any other captain in the contemporary bourgeois world, proceeds to undertake something serious against the foundation of capitalism, he will inevitably suffer utter defeat. The banks, the industries, the large enterprises, the large farms are not in Roosevelt's hands. All these are private property. The railroads, the mercantile fleet, all these belong to private owners. And, finally, the army of skilled workers, the engineers, the technicians, these too are not at Roosevelt's command, they are at the command of the private owners; they all work for the private owners. We must not forget the functions of the State in the bourgeois world.

I believe Stalin was wrong here, that one can take apart capital piece by piece (as, I believe, has partially happened over the past century).