So, I find strange this meaning that you give for a "draft" = that it is something that has connotation of throwing away when building the final product.
I think you are confusing a "draft" with a "sketch" and they are not the same.
I googled the term "draft" and here is what I found:
> "a version of something (such as a document) that you make before you make the final version" [1]
> "A preliminary version of a piece of writing." [2]
While "sketch" means:
> "a rough drawing representing the chief features of an object or scene and often made as a preliminary study" [3]
> "A rough or unfinished version of any creative work." [3]
> "A rough or unfinished drawing or painting, often made to assist in making a more finished picture." [4]
In the case of sketch I see some keywords like "preliminary study" or "assist" or "unfinished version" that indicates that the sketch will not be the final product.
So while it is true that a Draft could be thrown away if someone has new/better/difference ideas while working on it, it does not seem to imply that a Draft should be thrown when building the final product.
As far as I understand it is more that a draft will evolve into a final product or might be abandoned.
[1] https://www.merriam-webster.com/dictionary/draft
[2] https://www.lexico.com/definition/draft