A number of drawbacks to doing so exist.
Some people find extended reading on a computer monitor difficult and stressful on the eyes.
Also, you may be using a public access machine in the library or computer lab, and reading on-line might deny others use of the machine. Before you decide in what format you want to read, scan the E-text quickly to see whether it fits your needs. Scanning is especially important if your search leads you to numerous E-texts on the same topic. If the E-text you have found is copyable, make an electronic copy, which you can print out at a later time or read on your computer monitor. Some computing facilities allow you to print E-texts immediately.