It's pretty common for users to assume that once they comment on the issue, they are being added to CC e.g. github, gitlab, https://bugzilla.mozilla.org/ (I'm pretty sure it does that). However, when _unfamiliar with bugzilla_ user comments on the bug they haven't opened they won't be CC'd by default, because adding a comment is a separate button to _add to CC_. The only way for them to get CCed is by clicking the button at the top to add to CC list or preemptively change the setting in their profile (most won't do that). The issue with that default is that if user wants to help troubleshooting the issue and testing proposed patches, they won't be notified until they ensure that they added themselves to CC. The users not wanting so, can always set to the current default of _Never_. There was a bug #116417 18 years ago, but I think the functionality wasn't there yet and it sounded like there was no way to opt-out, since developers are minority and they can always opt-out in their preferences. The default bugzilla.mozilla.org is using is "Only if I have no role on them".
Discussed with Robin and we agreed to change it -- done via 'default preferences' in admin panel. 'Automatically add me to the CC list of bugs I change' is now 'Always'. People can override this in their own Preferences if they wish. Thanks!
(note: I considered 'only if I have a role on them' but at a skim, it looks like that only covers reporter/assignee/qa contact?)
