Note that the very mechanism of "deferring display updates" and thus relying on a VM-side composition buffer could actually be a feature with a larger impact. However, I am not aware of a single project that relies on this other than Morphic window dragging. Many graphics-related Smalltalk projects are rather fiddling around with hardware acceleration via FFI or custom VM plugins. That is, the primitives 126, 127, and 231 are not that useful outside Morphic and MVC. And for those projects, BitBLT (i.e., #copyBits onto Form) might only be a fail-safe if anything.
Looking backwards at older images, macOS users can still (a) enable fast/ST80 window dragging or (b) manually enable the image-side composition buffer as described above. That is, if the users are even able to open their older at all, which is tricky for 32-bit images on a modern macOS version.