For one, it duplicates the efforts in checking for prior reports. I might try 5–6 sets of keywords, but now I have to do so for 2 separate trackers.
Tickets cannot be moved between trackers, so instead folks resort to duplicating it and moving discussions… which is entirely opaque if you’re following up via email: you won’t get any more notifications and your future replies are silently discarded.
As a maintainer, having two trackers per project never made sense to me, so I’ve disabled discussion everywhere.
This is mostly a criticism of how GitHub implemented this feature, not of the decision taken here.
You can convert an issue to a discussion and vice versa, so no duplication is needed and your notification should be preserved.
Or do you mean something else?