But that is a different issue than "lowering the bar".Industry wants to get people that know more of what the market requires rather than just what the academic community wants them to learn.
The formal educational process is limited by the constraint on the time and money available. It's matter of "return on investment" and teaching/learning marketable skills takes priority over other areas that are perceived to have little or no financial value.
Notice that I specifically used the term "good enough". If there is a need for mechanical engineers to know, using your example, how to specify threaded fasteners and mechanical engineers are not learning this, then that fails the test of "good enough", doesn't it? Reducing the expectations that mechanical engineers know some esoteric academic thing will not all of a sudden make them know how to specify threaded fasteners. It's quite the opposite, in fact. Presumably at one time mechanical engineers did leave school knowing how to specify threaded fasteners and, over time, the bar kept getting lowered on what was expected until, finally, that dropped out of the curriculum (and while it might have been to make room for that esoteric academic thing, the reason doesn't really matter). If that was needed to be "good enough", then the bar dropped too low, but because it is hard to tell that being able to specify threaded fasteners is a necessary part of being "good enough", it got dropped and engineers are therefore being graduated lacking that skill.