Ubuntu Mate 19.04 doesn't read login.defs


I'm trying to set the PATH for TeXLive as it's recommended for Debian; that is, in /etc/login.defs, prepending said PATH, like this:

ENV_SUPATH PATH=/usr/local/texlive/2019/bin/x86_64-linux:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

ENV_PATH PATH=/usr/local/texlive/2019/bin/x86_64-linux:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games

But it doesn't work at all, even with a restart. I know that putting it in /etc/environment works well, but I would like to know why UM doesn't read login.defs.