My mirrored run gave me ten 1-star gems so the mirroring essentially gave me a free 10 gem power. Some of my clan-mates got a lot luckier than this though…
When people buy a lottery ticket, almost all of them lose their money, and the most common prize is the lowest denomination, e.g. $10 or something. This event is precisely like that. Most folks won’t get the gems they wanted, or much free gem power, but it’s all a bonus compared to not having the mirroring.
It’s literally free stuff and people complain about not getting enough free stuff due to getting unlucky with a virtual dice roll.