Not to mention the probability of getting them is so vanishingly low I can't imagine they are very widespread. Once a month you get CVC, where you get a handful of rings for specific factions. So you need to hope you get one for the specific faction you want, and then you need to hope you get the right rolls on those rings.
I would guess that some of your missed crits aren't because of these rings, but because of weak affinity... but in any case, they only just introduced these rings to offer an alternative way of fighting against pure speed nukers, I doubt they're going to nerf them now.
my attack champion is void and can only single attack so the first hit is very important to me because of this ring the first hit was wasted many times and I was defeated many times