The tradeoff isn’t dev job easy vs better performance. The abstractions allow devs to build faster or work on things users care about instead of unobservably better performance.
Oh no, the devs back then were for sure taking all the shortcuts they could, there just weren't as many ways to leave problems for the users compute to solve.
Which is such a capitalist lens to look at things through. Optimizing for a very small window of reality.
It's the same sort of optimization that drives behaviors where corporations feel no need to contribute to open-source projects. The same projects that enabled those very corporations to exist.
Back then devs were not taking shortcuts, it was the C API or bust, and it very much shows how far we have regressed.