All,
It is interesting how a single question can have so many different opinions in response!
My thoughts after reading through all of the posts is “it depends”.
If you want to know your company’s carbon footprint in the classical definition, you probably should not incorporate scope 3.
I you want to know the carbon footprint that your company has some responsibility in creating, maybe you should incorporate scope 3. I used the word “some” because your company may have varying degrees of responsibility - I have no idea how to determine this.
It seems to me that the carbon footprint approach, whether from the personal, household or corporate level speaks for the embodied and operational carbon emitted by your actions within the entity you are considering. If my household conducts a yard sale, is it responsible for the embodied carbon of everything we sell? If my household buys a product from Amazon, is it responsible for the embodied carbon in that product?
The argument that designers should consider their control over embodied and operational carbon as their responsibility is in my opinion a moral obligation argument which I agree with.
Thanks for all the great responses and questions!