And interesting, Mike Acton's point goes all the way back to the late Fred Brooks. Not the popular main topics of MMM, but the "Surgical Team" chapter, where he mentions that there should be someone taking care of the tooling. Now, in 1974 this could have been a person. In the 90s game studios it was common to have specialized teams building reusable tooling. This seems to be disappearing.
My original point, that was not well articulated at all, was more that there should be a middle ground. The choice shouldn't be only between "homegrown engine" and "Unreal/Unity oligopoly".
I'm saying there should be much more competition when it comes to third-party engines, but also in third-party tooling and third-party middleware.
And this competition should be more specialized in order to demand less of the "train and maintain a proprietary engine" but also less of the "dealing with roadblocks in UE".
(A lot of people think it's a custom engine though.)