In a nutshell: Minimal quality control in the production process, and zero quality assurance measures in place due to rampant corruption. High strength steel requires careful control of melt temperatures for specific periods of time. Also alloying agents need to be added at precise times and in precise amounts. Lastly - the pouring, forming, rolling and cooling steps also require precision and consistency. In the absence of same, garbage in equals garbage out.
TLDR: In general their manufacturing just sucks ass.
I think they’re able to, they can easily follow a formula. But not sure they make quality steel for their own manufacturers. Just because they can doesn’t mean they do.
Oh they are able - particlarly with products at the lower end of the technologic spectrum. Low alloy steel used in various grades of reinforcing bars for concrete? No problemo. High strength high alloy thermal steel like Invar that requires high precision to smelt and cast? Not so much. Under threat and coercion for military use? Certainly. But for general export in commercial markets @Solstiare 's response is the rule.