Because you might not like the associated drawbacks. Linux (and the BSDs) have shown that a monolithic kernel can be modular and well-organized. Mach’s descen

Because you might not like the associated drawbacks. Linux (and the BSDs) have shown that a monolithic kernel can be modular and well-organized. Mach’s descendants, L4, etc. have shown that if you want decent performance you either have to redefine “microkernel” or you have to put in an incredible amount of work to implement your simple design.