[creshal]

Windows 2000 has

- full UTF-16 support, l10n was painful on purpose for licensing / differential pricing — Microsoft simply didn't want people in rich countries to grab MX/PH licenses and swap over to English/Japanese/other G7 languages. With the far more aggressive licensing schemes of XP and later that was less of a problem.

— Full IFS support, to allow arbitrary, high performance filesystem drivers. Win2k was just obsolete by the time those were mature enough to really use

— A full NT kernel with support for swappable userspaces. The POSIX subsystem was deliberately crippled by MS to fulfil federal requirements without allowing real interoperability, but nothing would've stopped them from doing a WSL1-equivalent BSD/Linux subsystem. (WSL2 would've been impossible simply because hardware virtualization for x86 didn't exist)

None of those features really need the full array of modern bloat, where even hitting the start button can take seconds to refresh all the adverts.