Apparently nobody wants to take the 'secure default' performance hit of setting CONFIG_INIT_STACK_ALL_ZERO , as it will look slower compared to other distros.
As far as I can find that flag seems to be clang specific? Which distros even use clang? Also since the Kernel is not pure C not all safety options are safe, at one point a few distros enabled stack overflow protection, only to end up with a kernel that randomly corrupted application stacks.