While these Notifications might be informative and perhaps useful to some, the additional email traffic they generate is unwelcome for many people, especially if their Inbox is already very busy. They are likely to be deleted without being read 'messages' and are as annoying as SPAM, plus their effectiveness may be like the "Boy Who Cried Wolf" all the time.
Automatic 'System Notifications' remind me of websites that require clicking through many pages to get to desired content, apparently to achieve a Marketing goal of high 'click rates'.
They may be good/great for those that want all the extra messages, but an unnecessary nuisance for others;
e.g. I have a Group that had 311 messages in 20 years for its monthly in-person meetings (Dances, and Musicians playing and/or singing), which Covid-19 has canceled indefinitely. I created 2 Wiki pages listing various online events that may be of interest which I've updated 313 times total in 69 days (as I discover them, often at the 'last minute').
These new notifications would have increased its message frequency rate from 2 to 136 per month!
Yes, after the 'shock' of the first #wiki Notifications, I have set: Hashtags > Edit Tag and checked the No Email box.
I do not look forward to having to do that for each new #hashtag surprise, and for each of my Groups
Hashtags (and Notifications) are like graffiti - some people like/love them, others want to remove and prevent them.
I already had Admin > Settings: Message Policies
-Hashtags Required (unchecked)
-Hashtags Permissions: "Messages from members can only be tagged with existing hashtags, new hashtags will be removed."
-Hashtags Prohibited (checkbox)
-Hashtags Permissions: "Messages from members tagged with hashtags, hashtags will be removed."
-Hashtags Permissions: "Messages tagged with hashtags, hashtags will be removed."
-Hashtags Permissions: "Messages tagged with hashtags, will be Moderated."
Allow Moderators (with permission) to Edit Message (in Archives) to remove hashtags
Unless there is a Security need, features should be Opt-In (which is respectful), rather than require awkward and time consuming Opt-Out workarounds to curb Groups.io 'Junk Mail'.