It's been quite a while since I wrote any LaTeX, but you could compile a LaTeX document into ePub if you wanted to. In essence, LaTeX is the source code for the document, and the output is whatever target it is compiled to. So, if it is compiled to pdf, that is what you get, but nothing fundamental prevents it from compiling to other formats, given that someone writes the compiler.
I mainly used LaTeX when going through university, but after that my use is so casual that Word is more than good enough (think short letters and the like to parents or boardmembers). For documentation and notes Markdown works very well, and certainly much simpler. At work I use a mix of Word because that's what the other non tech people use, and Markdown for documentation.
