Lack of Roadmap

Linux has no central steering committee, design specifications, etc. It has many leading bodies for the many ongoing, and often competing projects. Some of the projects work on integration, overall consistency, etc. The value of their concepts is verified in practice.

Following Hegel's (and Parmenides) thought, one may expect that what is rational comes into existence in Linux, and what became a permanent part of Linux did so because it was rational (Hegel's original is "What is rational is real and what is real is rational"). The same cannot be expected to be the end-product of development of a system build to a rigid blueprint prepared by a committee.