A TeX picture environment that uses Scheme as its extension language TeXmacs 2.1. Microsoft Word and WordPerfect contain subsystems that essentially emulate the older eqn system which was one of the alternatives that Knuth found inadequate for professional use. Based on their architecture, TeX and LaTeX cannot do the typical Word thing, which is to crash and destroy your document. Documents can be moved to all of the kinds of platforms listed above, and platforms that are still to come. LaTeX has been quite good at supporting old documents with newer software.
Output is vastly more attractive than that produced by word processors.
It provides robust tools for managing components of complex documents such as figures, references, bibliographies, table of contents, indexes. The use of text also provides improved portability and robustness. Text management tools such as RCS can be used to quite efficiently manage documents. There is no problem in throwing simply enormous documents at TeX or LaTeX . Just for grins, I tossed some formatting at start and end of a copy of the Gutenburg Project edition of the King James Bible, and threw it at LaTeX .