Relatedly, the /etc/skel/.profile file indicates that “the default umask is set in /etc/profile”. This is not true: /etc/profile contains nothing about umask (at least, in a freshly installed Debian Bullseye). In fact, even adding a umask command in /etc/profile seems to have no effect in a Gnome session, maybe for reasons indicated at https://unix.stackexchange.com/a/254923/.
I think it would be important to correct that comment: we ought to give correct indications to at least those people who bother reading the doc.
