Precisely. I write mostly in TeX (real TeX, not LaTeX) but use LibreOffice for some documents. One of the major reasons that I continue to use TeX is that I can edit it as I please, which generally means using GNU Emacs. LibreOffice and its kin are so much inferior as editors that I feel crippled when I have to use them. Indeed, when writing something that is mostly text, even if it is ultimately going to be formatted in LibreOffice, I almost always write it as plain text in Emacs, then import the plain text file into LibreOffice. TeX is also easier to edit using other Unix text tools and to generate programmatically.
Perhaps surprisingly, I have also found it much easier to produce documents with a lot of images in TeX (using the psfig macros and dvips/dvipdf) than in LibreOffice. LibreOffice tends to get sluggish and to give me a hard time getting the images scaled the way I want them.
