I think the critique is that you're applying this too narrowly to front end developers. Pretty much anyone who has been around long enough has met someone with

I think the critique is that you're applying this too narrowly to front end developers. Pretty much anyone who has been around long enough has met someone with years and years of experience doing exactly one thing, whether that's WordPress or java CRUD or something else where they have blindingly obvious gaps in their knowledge that someone with their experience shouldn't. The lack of deep knowledge isn't limited to a single field.