That's true for the case of simple apps that use a single runtime. Lots and lots of work is done "in Java" or "in Go". Lots more, including most of the larges

That's true for the case of simple apps that use a single runtime. Lots and lots of work is done "in Java" or "in Go". Lots more, including most of the largest and most complicated[1] apps, require synthesis of lots of tools from lots of sources. Those apps need to work very hard to get their heaps to play nicely with each other, and the tuning required by modern collected runtimes tends to blow up in strange ways. [1] And especially including the ones targetted by the Boehm collector in the linked github. Also apps for which Rust (which famously eschews a collected heap) tends to be proposed.