A more detailed description you find on the website, too
Main reasons (copied from the website):
- They charge exorbitantly high prices for subscriptions to individual journals.
- In the light of these high prices, the only realistic option for many libraries is to agree to buy very large "bundles", which will include many journals that those libraries do not actually want. Elsevier thus makes huge profits by exploiting the fact that some of their journals are essential.
- They support measures such as SOPA, PIPA that aim to restrict the free exchange of information