Okay, so we move to microkernels, which murders everybody's performance because we still don't know how to work around context switching being expensive, and force everyone to do the constant additional effort to define exactly what components should have permission to access what parts of their system (unless you want everybody to use one-size-fits-all defaults and lose functionality, or just give everything more permission and lose the security benefit). Now in this hypothetical world, an SMB server has a vulnerability. Technically, the situation is much improved; in this situation an attacker only has access to whatever that component had access to. So, just all the files you shared, and (hopefully read-only) user information. And probably network access. Is that really a good cost/benefit trade?