You argue that powerful open-source tools should lower the barrier to entry. That's probably true. But I think there is also some differentiation that happens:

You argue that powerful open-source tools should lower the barrier to entry. That's probably true. But I think there is also some differentiation that happens: the best developers are able to learn more tools and squeeze out more productivity. So a highly motivated and somewhat clever engineer can do a passable job of ops/db/backend/frontend/design on their own, which makes them quite valuable to businesses. FAANGs are a bit of a different story, as you point out. But they also have a lot of infrastructure and culture in place that allows specialists to work efficiently.