I want to disagree with you, he seemed to specialize in JS, in his post he mentioned that almost 50% of the time he worked in erb that's the rails template to p

I want to disagree with you, he seemed to specialize in JS, in his post he mentioned that almost 50% of the time he worked in erb that's the rails template to produce html, or the "new fancy" term that JS developers call server side rendering. So frontend is focused on whatever produces something visible to the user, most of the time html, others can be jsx or whatever the frontend template is being used. I think this shows why he was not hired as senior, he's lack of experience/knowledge in the area.