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.
The benefit is that all users who just ask for help, assistance, or are unable to install or use the software now have a place to ask.
You shouldn't create an issue just because you get an error when installing, but it might be beneficial to still ask for help.
If it is indeed a bug, then create a ticket, linking to the discussion.
Normally, too many issues are user errors.