Many web developers just know how to glue together framework components. I recently installed a Nest, attaching the requisite wires from the existing AC system; I have no right to call myself an HVAC technician. However, you see a lot of the same happening with web developers that can't go much further than copy and paste code from a blog post or Stack Overflow. The difference is of course that they are being paid good money and are supposed to know how to move beyond the basics.
I believe we'll see a purging in a few years, similar to what we saw when the bubble burst in 2000/2001.