Amazon -- Deliver docs to PC or MAC

I still do not understand why the option of sending personal docs to PC (or Mac) kindle is disabled, there a couple of workarounds:

Option 1)

PC, right click on the document and open it with Kindle.
Mac, open with Kindle.

Option 2)

Find "My Kindle Content" folder and drop your document there.
Linux command [find / -name 'My Kindle Content']

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