Microsoft reacts to marketing pressure to make design decisions favoring running a few processes faster but then finds itself forced first to layer in backward compatibility and then to engage in a patch-and-kludge upgrade process until the code becomes so bloated, slow and unreliable that wholesale replacement is again called for.

Whereas Unix

…in total contrast, Unix developers advance systems research to provide both long-term continuity and continuous improvement in the software’s ability to do more or better with respect to things like throughput, reliability, security and communications.

Exactly.