Publishers did not produce PDFs or ebooks, so only self-published writers wrote ebooks.
Today, there is the Kindle, the Nook, the Kobo, and a variety of other ebook reading devices and apps.
Ebooks are, today, as real a book as a physical book.
A book is the content. It's the words you write. ...and sometimes the design or the experience. It's no longer just the 'thing' you are holding.
The best publishers and self-publishers produce physical books and ebooks.
I think Writers Digest and Digital Book World call the books that self-published writers write ebooks because they think self-published writers aren't real writers.
If you call what you write an ebook, you're telling the world you're not a real writer. Write a book, and if you do things right, you'll have both physical books and ebooks.
Be a writer.
Be a real writer.