If a man as brilliant as B.H. Roberts, who knew LDS history and scripture as well as he did, felt socialism and leftist political views were consistent with Mormonism, it seems silly for Droppy, BC Space, LDSfaqs, et. al. to suggest otherwise.
And Mr. Roberts, if such is actually the case, was wrong, and devastatingly so. We can play the my-General-Authority-can-beat-up-your-General-Authority game all the day long, but the fact remains that corralling and deploying isolated GAs against the overwhelming consensus of General Authority teaching (the way EV Christians isolate and deploy Paul against the rest of the New Testament regarding the nature of grace) over nearly two centuries (as well as against logic, critical thought, the laws of economics, and thousands of years of human history and experience) is an exercise in futility.
The crux of the matter is that what we call "Leftism" or "Progressivism" is, in point of fact, a central hub of the Great and Abominable Church of the Devil the Book of Mormon foresees would have the entire world and its people under its boot in the last days.
There is no let's pretend about this, nor that the core principles of the the Left, Progressivism, "social justice" movements etc. are, at their core, part of the ancient and ever reemerging pattern of anti-Christ, also spoken of in the Book of Mormon. One can be a part of and supportive of one, or the other, but not both.