LaTeX is very rich; other tools support much less

• Margin notes: LaTeX, HTML with tailored css code
• Footnotes: LaTeX, Sphinx, reStructuredText, MediaWiki
• Bibliography: LaTeX, Sphinx, reStructuredText, MediaWiki
• Index: LaTeX, Sphinx
• Hyperlinks: all (but not on paper!)
• Interactive programs: Sphinx, IPython notebook, raw HTML
• Searching in multi-page doc.: Sphinx, MediaWiki, LaTeX PDF

Highly non-trivial to translate from/to LaTeX!