That was the rhetoric but not the reality. That has never been the outcome of Marxism even when it was a central tenet of the belief system. While outright commies did some of the heavy lifting in things like the 40 hour work week, workplace safety, etc. it wouldn't have happened without a lot of the non-Communist left or outright conservative worker's groups, many of which outright detested Communism.
It depends on which Communist country. USSR? You're right. China in the beginning? They lionized The Worker and really did take strides to elevate them as high as they could, while shitting all over educated experts like engineers.
Take Chinese military weapons for example. In the PLA the SKS, specifically the Type 56 Carbine variant that was domestically made in China, was the primary infantry rifleman weapon for a VERY long time. They issued it well after it had become obsolete as a frontline combat rifle and better, more advanced rifles had been introduced. They issued it despite having their own domestically made copy of the Kalashnikov was available and in production, the Type 56 Submachine Gun. Part of the reason it stuck around so long was because the PLA had built up mythology about the brave Chinese rifleman bringing a more capable, more advanced, better equipped enemy to their knees with accurate, well placed, well timed, disciplined fire.
They did want to modernize and develop a replacement for the Type 56 SKS, and tried several times. One of those attempts was the Type 63, which was kind of a mix between the SKS and the AK. The idea behind the Type 63 was a lot like the M-14: a product improved upgrade of the rifle design it was replacing, and using much of the tooling and machinery that was used to manufacture it's predecessor. Only the Type 63 was actually "successful" in actually utilizing the tooling and machinery that was used to manufacture the Type 56 SKS. It looked very much like an SKS with it's fixed 10rnd magazine replaced with a detachable 20rnd magazine, but it had a rotating bolt based off the AK instead of the SKS tilting bolt, and it maintained the SKS short stroke gas piston. It was also select-fire like the AK instead of semi-auto only like the SKS. It was designed to be as economical as possible and to use as much SKS tooling and machinery as possible, so it would be quick and easy to transition to Type 63 production.
The prototypes were pretty decent rifles, and in testing they rated better accuracy than both the Type 56 SKS and Type 56 AK. The experts spent a lot of time and effort designing a good, affordable, accurate, reliable rifle for the PLA. And then they were adopted as the new official rifle of the PLA and went into production. The early ones that followed the blueprints faithfully were good weapons. But it wasn't long until it all went wrong.
Remember how I told you how much China during the Great Leap Forward lionized The Worker? Well, there was this trend in the early days of the CCP where workers were encouraged to come forward with their ideas to "improve" production of products or the yield of crops. Over 700 unauthorized changes were made to the Type 63. The milled steel receiver was replaced with spot welded stampings. The barrel was changed from being threaded into the front if the receiver to being press fit and pinned in place, because threading takes time and specialized tools, and they could make the barrel a bit shorter by press fitting it and save on materials. These were all just "bright ideas' that The Workers had while producing the rifles.
Now, I'm sure you're asking "How could this happen? Surely they would have had quality assurance officers inspecting the weapons, or a project manager who would have insisted on testing these changes before applying them to the whole production run, right? Or they would have gone to the experts who designed the Type 63 to get their take on the matter?" No, of course not. As I said, they were all unofficial changes that were done, because the inspired brilliance of The Worker shall not be questioned. And those experts? They're just academics and eggheads. No one cares about what they have to say, despite the rifle already being designed to be as cheap to produce as possible while still being a decent military weapon.
It wasn't until the rifles got into the hands of the PLA and getting used that they realized what a disaster these changes were. For one thing, the rifles wouldn't hold zero. Their point of aim would change on the same rifle, sometimes hour to hour. They shaved down the sides of the wood stocks as much as possible to save weight. Well, one thing the PLA loves is the bayonet and doing bayonet drills. They changed the knife blade style bayonet from the Russian version of the SKS to a cruciform spike bayonet on the Chinese Type 56 because they were snapping the blades of the knife blade style bayonets during drills. The Type 63 retained the spike bayonet. Well, when it came time to do bayonet drills with the Type 63 they were breaking the stocks because so much wood had been removed. Oh, and the damn things were literally blowing up in the faces of their shooters, sometimes lethally.
Eventually the PLA refused to be armed with the Type 63 and they had to reissue all their old Type 56s, which at that point were supposed to be going to the police and militia who were still using various old bolt action rifles like the Mosin-Nagant carbine, Mausers, and Arisakas taken during the Japanese occupation of the mainland. But if it hadn't been the Chi-Coms cult like reverence for The Worker and their absolute disdain for educated experts, the Type 63 might have actually been a decent and successful replacement for the old SKS.