I get his frustration all too well. Experienced that vert same bs in every place I worked. Even see my own mom's health going down because on it.
Which is co-workers getting too damn comfy in their own lower positions that they dont bother trying to grow or learn more because they become too over reliant on you. Than expecting a day may come when you cant be there to wipe their asses. But because of that work culture. Most jobs never think on that or keep putting it aside to train a alt.