Social media posts—and especially tweets—are microwaved insights which often, in their composition, have been zapped of all the intellectual nutrients which might have made said insight functionally beneficial to the consumer.
A good book is a long-form thought, researched and considered from multiple vantage points, and presented in an order and with a technique that is designed to bring forward meaning that may be usefully applied in some meaningful manner.
Not all books are good books, of course; but a good book requires a certain discipline... of both the writer and reader. The writer must have the discipline to follow-through on the development of the thought, and the reader must have the stamina to engage through transitions and into details, over pages, sub-sections, chapters, and parts to meet the writer at a place of depth not available in a 280 character post.
The consistency of the small ideas woven together into a tapestry of one long-form thought is an intellectual exercise for both the writer and reader that dwarfs the method of communication in social media platforms. It requires a patience and commitment that evokes a higher plane of wisdom and insight.