The most broken hax is kotoamatsukami.

You don't need to make eye contact for Kotoamatsukami to work, who told you that? Danzo had bandages over his eye and Shisui was using it from miles away.

And I believe like the Tsukuyomi, not even Tailed beasts are safe, since Kotoamatsukami is considered above Tsukuyomi.

Hmm, we will never know for sure unless the author shows that in the series. Right now we know that it doesn't require eye contact, it makes the other person do what you want, and it makes them think that's what they want to do as well. So... They don't realize they are under genjutsu.