I can still remember an old conference when Microsoft bragged that running windows-only allowed them to remove 20-30% of the Sybase code base as they didn't need the cross-platform cruft. It would be interesting to see how they code for cross platform portability now.
https://twitter.com/TobiasSQL/status/798937457916002304
>The Platform Abstraction Layer (PAL) powering @SQLServer on #Linux evolved from the MSFT Research Drawbridge project