I firmly believe that just its name set TeXmacs back by a lot. It's a pretty great choice, was even more so a decade or two ago (when typst and the ilk weren't available). But every single time I've tried to introduce it to someone, it's always some variant of "Oh, I don't use Emacs, so a plugin for that isn't useful to me". It's a really unintuitive and unfortunate naming choice that I wish they'd at least changed at some point along the way.