Communists typically advocate voting for worker parties, such as the PSL. It isn't that voting itself is a problem, it's that placing our energy behind getting an imperialist party elected rather than the other is energy that could have been spent on growing the socialist organization. From the perspective of an individual, voting doesn't take much time at all. From the perspective of an organization, election season takes a tremendous amount of effort, no matter which way you push for. These are the kinds of problems you run into when organizing that aren't immediately obvious for those that are used to seeing political participation as purely an electoral measure.