Overcomplicated, and involves even more places to check for issues.
Comment section is good enough for this.

It becomes too many points of failure and too much mental overhead,
juggling issues, comments, emails... its too much... and is why if I do
choose to maintain packages again, I would 100% exclusively keep it to
the AUR and not push it elsewhere, so many people recommend that
workflow but it simply doesn't work.

Issues are simply a more organized way to write comments; they won't co-exist. It can be weird to follow multiple threads at once and get a lot of notifications when you only want to follow your thread. I've also seen people abuse/misuse comments partly due to its name ("comments"). Issues offer more control of notifications and have an actual ping feature.

-- 
Cheers,
Aᴀʀᴏɴ