In both accidents the pilots failed to fly the aircraft IAW NON NORMAL procedures, they did not work as a crew to try and resolve the issue at hand and got too distracted by the stall warning system.
A runaway stabilzer is a non event if the procedure is carried in full and the aircraft flown correctly.
But I suppose most pilots I flew with where very well trained.
Ethiopian isn't some dodgy third world carrier. They've had a fatal crash caused by pilot error this century, but then so have American Airlines, Southwest, Singapore Airlines, Air France, Emirates. Before that you have to go a long way back to find a significant case of pilot error resulting in fatalities. As far as I can see their record isn't littered with regular incidents which you would get from a Lion Air type carrier. From what I gather the Ethiopian Aviation Academy is highly regarded and the airline is staffed by a fairly experienced mix of local and expat Training pilots.
Hard to fly the aircraft in accordance with non normal procedures that would allow you to control the aircraft if those procedures are not in your training manuals. I think the grounding of the type for two years until the necessary rectifications were made is a sign this is primarily a design fault and lack of correct information passed to pilots rather than pilot incompetence.