Yes, Donald Knuth is a hero and a true renaissance man, and his TeX is an unsurpased achievement, a tool of lasting value.
Back in 1996 I took a few months off for an in-depth study of Knuth's TeX: tokens and boxes and output routines and all. I used plain TeX to write a flexible little macro package for myself, with a minimalist input syntax, set up for my own writing, tailored to my own writing needs.
I still use that same package today, 30 years later, unchanged except for project-specific adjustments. All the materials I give to my students are written in that package, all my papers. A stable writing framework for a lifetime. Few other systems have such stability and power. Thank you, Donald Knuth.