> i read third party epubs on kindle all the time.

No, you do not. Kindle has never and, as far as I am aware, to this day, does not support epubs. The only way to read epubs on your Kindle is to convert them either by Amazon's Send to Kindle service or through software like Calibre.

It has the appearance of working like this:

  1.  Epub of a book exists on a computer
  2.  User takes simple action to read that book on a Kindle device
  3.  ???
  4.  User succeeds at reading that same book

Like when Github invisibly renders Markdown into HTML for display in my browser: It seems rational to say that I'm reading a Markdown document.

Or when I print that same HTML onto paper and read it. I'm not reading the HTML nor the Postscript intermediates: I'm still reading a Markdown document.

dont care about all that. ppl are really reaching here by moving goalposts .