Why don’t tau have access to any 5+ critical abilities?

It feels like most other armies have at least 1 stratagem or enhancement that gives them access to a 5+ criticals whether it be hit or wound but excluding Kroot tau don’t get that. Why is that? I was kinda thinking about it because I’d like to try kayon sometime, but since the damage boost comes so late i honestly feel like relying on 6+ for sustained hits isn’t worth it.