I’m a hybrid author in that my eight books are available through medium and small publishers, but I’ve also self-published four e-books, the first four books in my Paul Jacobson Geezer-lit Mystery Series because I retained the e-book rights to these. Since then my publisher has decided to publish e-books as well as print books.
The advantage of traditional publishing is that the publisher bears all the costs of editing, book cover design, production and distribution. Also, traditional publisher have established sales channels to get books to market. The disadvantage is the author gives up control and receives a relatively small percentage of the money earned.
The advantage of independent (self-publishing) is that the author controls the whole process and gets all the money earned on sales. The disadvantage is that the author must bear the upfront costs and take the time to manage and do much of the upfront work. Also, the author must bear all the brunt of sales and marketing of the book.
The hybrid world now allows an author to pick and choose which manuscripts to publish through the traditional route and which through the independent route. This gives the author the best of both worlds depending on the particular manuscript.