Comment # 6 on bug 1219979 from Dr. Werner Fink

Exporting functions is a bash special feature* and not supported by any other
shell or program like systemd and as all exported variables this belongs to
/etc/profile, /etc/profile.local, and /etc/profile.d/*.sh

Can we please stop misusing ~/.bashrc, /etc/bash.bashrc, and
/etc/bash.bashrc.local for environment? Those are for interacive invocation
only.
As the the profile is sourced at login via e.g. (/usr)/etc/X11/xdm/Xsession
in the exec_login() function to have the environmnet only once for the full
login session.

*
 werner@boole:~> xyz() { true; }
 werner@boole:~> export -f xyz
 werner@boole:~> printenv | grep xyz
 printenv | grep -A1 xyz
 BASH_FUNC_xyz%%=() {  true
 }

only bash knows about `export -f' and `BASH_FUNC_*%%=()' but not systemd