I have no idea who that user is, nor do I really care. A single unsourced opinion doesn't really matter.
>The materials used in the mass-production StG-44 were of poor quality due to war expediency, and British analysts (who praised the earlier MP43) found the bolt could be totally immobilised by pinching the sides of the receiver with the fingers of one hand, while the rifle could be totally destroyed by the simple act of leaning it against a doorframe and then knocking it over. The stock was prone to breakages, and American analysts criticised the 11.5 pound weight of the loaded weapon as excessive considering the relatively small round used, comparing the StG-44 unfavourably to the M1 Carbine."
I've come across those claims, but largely they're based on fault US intel reports that were more about maintaining US morale than being accurate; I've found one that claimed you could dodge MG42 fire because the weapon was 'too precise' and produced too narrow of a cone of fire. Modern US military personnel that tested bring back WW2 weapons, including STG 44s, did not find these wartime reports accurate. In fact I have BIOS report from the British which actually says the opposite about the weapon and considered it an ingenious wartime expedient; the Belgians ended up copying it and made the initial version of the FN FAL in 7.92 Kurz (it had a very similar operating system too).
The biggest issue historically with the STG 44 was the bombing making adopting it in late 1944 impossible en masse (the STG 45 was in no way likely to actually be adopted for the same reason), while bombing of chemical production facilities prevented the ammo from being produced in enough quantities, which in turn resulted in the throttling of production. The unissued STGs were so because of the lack of ammo; no point in issuing them if they couldn't be supplied with ammo.
Also as to the claimed issues with quality and concept, its funny that the Soviets, the one power with the most experience fighting against it never made any claims about it being overweight or flimsy and in fact copied the concept as quickly as possible, including the stamped sheet metal technology as soon as they could figure out how to get it to work (10 years after the war ended).
I have several sources, but the single best is this one: https://www.amazon.com/Sturmgewehr-Firepower-Striking-Revised-Expanded/dp/0889355932