Yes science can be a good guide. The trouble is that some left-wing social movements explicitly reject science (and Enlightenment values in general) as a tool of the oppressor. There are certain things you're not allowed to say regardless of scientific evidence. For one example, look what happened to scientific critics of Lysenkoism.
I don't think "not on a large scale" is a good argument. Small groups of people can be incredibly powerful. The people who founded our country could all fit in the same room together.
That argument is outdated by a decade or so. Sure, there's still some college students, but the ones from a decade ago now work in the big tech firms, NYT, etc.
e.g. basically all social science that investigates differences in ability/outcomes between genders or races is explicitly rejected by the left on the grounds that it's sexist/racist.
The left is certainly guilty of ignoring gun or crime statistics they don't want to hear, but it's totally disingenuous to compare them to folks in the hard right-wing camp, such as fundamentalist Christians or the hardcore climate deniers.
All I know is that both of them are perfectly willing to discredit and throw science to the wind if it doesn't fit their needs. I hope the science community realizes this before they let themselves be used as pawns by politicians.
That is also a problem, but stems from a different cause. The right wing accepts the validity of the scientific method, but claims that biased left-wing scientists have intentionally published skewed results in a few limited areas like anthropomorphic global climate change. I don't agree with this interpretation and I think that climate change is the most serious threat to human civilization. But in countering destructive extremist movements from both sides it's important to understand the basis of their ideologies rather than just labeling them as "anti-science".
I agree with your general point as to why some people are against science, but using an example from before the second world war to call out the left specifically is pretty off-base. An example from 1935-1940 in Soviet Russia has very little relevance to 2020 on an English-speaking forum.
Both sides of the spectrum have anti-scientific factions which are current: on the left there are deniers of gender differences and people who overstate the role of genetics in mental illness, on the right there are climate denyers, evolution deniers, people who think crime is prevented by more aggressive policing. Anti-vaxxers are fairly uniformly distributed across the political spectrum.
It seems rather tangential and doesn't contribute anything. It is pretty clear which country is being referred to if we're staying on topic, just saying "I like to use science as a guide" is an almost empty statement. Which science? Psychology, sociology, physics? The scientific method? How? Do you mean reading the current literature? How are you applying it as a guide to the current topic under discussion? The comment they were replying to cited authors and relevant terminology which is a great contribution for people that want to read more on the subject. This comment just blurts out an opinion and then follows it up with what could be considered a thinly disguised jab. Hence the downvotes.
I think it is because I attempted to be neutral and post the mental model I like to use (other commenter asked if scientific method and recent research and understanding. Answer to both is yes.).
This is why I like to use science as a guide (not a decision point), for then there is a chance to be self-correcting.