The interesting thing is that the other comment alongside yours is talking about GGG, who rolled their own as a team of about 6 (in the early days), and they're by far the most productive game developer I've ever seen.

I think Unity and the like have made the average project much more productive, but they don't add power to the top end. The power of having everything perfectly customisable by a team of experts with perfect domain knowledge is just too much for anyone else to match by getting quick wins off the work of others.