A list like this without the noise would be very welcome.
But a number of people would have to be on both lists, then, to see
all the input and for seeing who can be invited. That's more load, not
less, for at least a selected few who are all supposed to have some
more valuable things to do, given their qualification.
Creating yet another place also feels like a retreat.
If moderation, how about switching this list to initially-moderated?
Emails of new subscribers would either be allowed to the list, or
moderators would write replies stating the reason for rejection
(ideally in the most constructive, patient and friendly manner – thus
not a job for me –, with pointers to relevant past discussions).
Newcomers would be switched to direct-to-list after 2 or 3 "good"
emails. The reading and following-rules challenged could be put back
to moderated, or even disinvited.
A little quiz could be used as hurdle to subscription ;)