I don't blame coco for peoples problems.
Been using it since like 1999 with perfect success on vegetable crops and powder greenhouse fert (yes the compressed bricks too!)
We generally rehydrate the brick with a half strength or so nutrient solution and go to town. With proper runoff at each watering the coco becomes "buffered" real quick.
I do believe most people are feeding at the wrong ratio and wrong ec's with the wrong watering habits.
Looks like there is a trend with those in recirculating coco systems having much less issue. Probably cause they can see clearly what the ec is doing in the res and the coco is being flushed constantly