yes, indeed, the subject is annoying if you plan to
use the mailing list
as "super groups" to chat, I plan to setup mailing lists with that usage
but then it is a matter to configure the mailing list server-side,
for classic mailing lists it is useful to see the subject since most users
will be using classic MUAs and giving info in the Subject, this is especially
true for GitHub notifications where the Subject is the name of the Issue,
etc.
maybe what we need is not to show the subject mixed with the normal text,
provide it as a message property and let the UI/clients choose to not
display it or display it in a nicer way separated from text (for example
in a gray header with a color similar to the "forwarded message" color
or so
another issue is that you can reply to posts in a mailing list but you can't
create a new thread properly, since you can't set the subject and you will
publish something with a Subject "Message from Foo", maybe as a trick you
could create a group with the mailing list address and set the name of the
group to the desired subject but then you have to do that each time you
want to set the subject, sending messages outside the mailing list group
and creating several garbage groups you need to delete