The 1.5x Critical Strike coefficient does not only apply to +Critical Strike Damage.
The 1.2x Vulnerable coefficient does not only apply to +Vulnerable Damage.
The 1.5x Overpower coefficient does not only apply to +Overpower Damage.
There is an Order of Operations just like any mathematical formula. Additive Damage can be thought of as a single bucket. For all conditions that are met, that portion of your Additive Damage gets calculated.
If you don’t believe me, you can test this quite easily by swapping +Damage to Frozen out and see if your damage changes compared to an equal value +Critical Strike Damage.
This is why the basic gist is to take the highest value for the condition that is at or closest to 100% (after you have met all multiplicative bonuses or contributions).
Typically, individual Additive Damage to Crowd Controlles Enemies is a bad bucket to invest in.