“Also, deploying them properly takes intel, lots of training, support, parts, institutional knowledge, dedicated units etc.”
We gave the mujahideen these weapons and they did a pretty good job against the Soviets.
But it’s all, mostly, failing here. Bradleys, tanks, anti armor, AAA, the money,l... all of it.
So tell me why. I don’t know everything.
The Soviets weren’t expecting Stingers and hadn’t seen their performance in the field at the time. They also had some fundamental design errors in their choppers (like glass cockpit windows) which they did rapidly fix. Lessons from that went into the design of later gear, and in turn the West got some ugly surprises in Syria via Turkey.