"Modern" TeX processors (LuaTeX or XeTeX) are sadly held back because publishers still cling to PDFLaTex. For instance, ArXiV "fully supports and automatically

"Modern" TeX processors (LuaTeX or XeTeX) are sadly held back because publishers still cling to PDFLaTex. For instance, ArXiV "fully supports and automatically recognizes PDFLaTeX" and makes no mention of other backends [0]. So, LuaTeX is perfectly fine for personal stuff that you can compile in-house, but basically nobody wants to risk using it in any scenarios where sources are to be sent to a 3rd party for compilation, only to find out that they need to make them PDFLaTeX-compatible. And after all LuaTeX came out of beta in 2016 [1], which is pretty recent in TeX-years. So it kind of makes sense that publishers still prefer the quite battle-tested PDFLaTeX... [0]: https://arxiv.org/help/submit_tex https://arxiv.org/help/submit_tex [1]: https://tug.org/pipermail/luatex/2016-September/006201.html https://tug.org/pipermail/luatex/2016-September/006201.html