Confusion and retaliation are essentially sister status effects. One is a boon, and one is a condition, but both serves the purpose of punishing enemies for attacking. Retaliation only stacks in duration, but confusion stacks in intensity. That makes confusion too strong imo because it affects all skills that does not cleanse it, even auto attacks. Some builds are able to build over 15 stacks of confusion in a single burst combo. It's broken. This would be fair if confusion did not cause damage from every skill that does not cleanse it, but it does.
As long as confusion continues to affect auto attacks, heal skills, and even cleanse skills that fail to cleanse it, it should not stack in intensity. It should only stack in duration, similar to retaliation. And classes/builds should be rebalanced around that.
If confusion will continue to stack in intensity, then it shouldn't affect auto attacks, heal skills, and cleanse skills even if it fails to cleanse the confusion.
I expect a lot of backlash from this post, but this is my opinion. Confusion is too strong, and should be brought in line to the same level as retaliation.
TLDR: Confusion should stack in duration, not intensity, similar to retaliation. Balance classes around that, or make confusion not cause damage for using auto attacks, heal skills, and cleanse skills.