Isnt instable infusion completly out of place in the assasin tree?

https://www.pathofexile.com/ascendancy/classes/Assassin

10% chance to gain a power charge on non crit strike

Its a class that specializes on getting as much crit chance as possible, on top of that the big node following it gives you essentialy 100% crit chance on most stuff making that node obsolete.

Whats the deal with this? Just something bad trown in there so that the classes isnt even more OP?