You seem to have some axe to grind about this, but it's not really helpful. Engineering management is hard, and a number of skills and traits are necessary. If ICs are willing and able to be promoted that's great, but it's not a panacea. When it comes to early scaling, even with the best of intentions the bottom line is you may be growing faster than existing folks can acquire the requisite skills. Of course hiring from outside runs the risk of cultural damage, but promoting from within runs the risk of dysfunction via the Peter principle. Choose your poison, but at least you're growing right?