Many roleplaying products come in both a physical book and an electronic format (typically a PDF). So what do you bring to the table? A computer or tablet with PDFs on it, or a physical book?
Unless the resource is only available in an electronic format and you cannot print the relevant page(s) to bring to the table, I find that computers tend to be distracting. An electronic device cannot be put away as easily as a book when not needed.
I suppose an exception could be made for a published adventure, because you will generally always need it to be open and you can always lock the device when you are taking a break so YOUR PLAYERS CANNOT SNEAK A PEEK AT WHAT IS COMING.
An argument can be made that a computer / tablet can hold several books in the space of a single book…but should the GM really need 47 different books to run a game?