I read all the comments and my response is this...

First of all, there is no limit to the amount of emails that discourse will send out.  That is a site parameter, and whomever supports it for Fedora needs to change it: 

If the requirement is that discourse completely replicate 100% the functionality of mailing lists, that is unreasonable and isn't going to happen.  As I mentioned earlier there are several groups working on this or have done migration from mailing lists to discourse:

You can find more examples with a web search.

A key comment was:  "Our site is still quite busy, although some people are still grumbling about the change, 8 months later. The die-hard email users are still able to participate, which came as a bit of a pleasant shock to them. I think they were fully expecting that once we moved to a modern platform, they’d be forced to use a web interface."

Personally, I don't like my mailbox filled up with mailing list postings.  I prefer to uses the discourse rss interface to scan for topics and then go directly to it to respond.  Instead of writing a "me too" email, I can simply click a like button to show I'm in agreement.  It's easier to see the full context of a thread.  With the current situation I have to go scan the archives. I like to use the mobile app to read and reply from my phone.  For every item mentioned about discourse doesn't do A, B, C with mailing lists I can counter with an item that email lists cannot do.  The fact is that for the vast majority of people, the discourse mailing list functionality is good enough - and as time goes on it continues to improve - but again, it's not reasonable to expect or demand 100%.  IMO the pros outweigh the cons.

The top of this email thread is:  No longer supporting mailing lists

and my understanding is that Fedora is searching for people to take over support.  Seems to me that is a good time to consider switching to discourse.  From reading experiences of people who did the migration, it's easier to support.