Because objects don't add to damage dealt. They add to damage value.

So first you had the d6 increasing damage value and then the +2 also increasing damage value. There were two things potentially increasing damage value.

Damage dealt was never even an issue in this instance, hence the reason the damage dealt bit wasn't modified in the PG.

I ignored nothing. Instead, it looks like my reply somehow got into the quote box. For reference:

That bit there was your answer.