A lot of work went into determining why they were failing and the damage trail led to the problem being static electricity. This was the beginning of learning how to control these charges. There were many non-believers in the late 70 s and early 80 s that felt that a static charge could not damage or destroy integrated circuits. Even today there are some engineers that believe static is an overblown issue. Today most companies recognize the value of a complete static control program.
Integrated circuits have different levels of sensitivity.