To create macOS and other applications, one needs to upload blobs with the necessary components first. Then, to create the actual application to be assigned, one use the proper API to point which blogs are used for that Application.
However, in this process, often blobs are uploaded twice or more than that, and the user is responsible for his own bookkeeping of which blobs have been uploaded in order to delete unused blogs. And worse: if the user attempt to the the DELETE blobs API call, the result is always 200 (successful), no matter how many times you run it.
In short: there is no way to provide the user with proper information on how many blobs are on the server, nor if they are in use.
Therefore it is important to be able to retrieve a list of blobs that were uploaded and if they are in use by any application.