The sheer amount of information available on the Internet can be overwhelming for students, and they may have difficulty finding specific data without getting caught up in social media or other distractions. It can also be difficult to verify information found on the Internet. So I think using the Internet harmful to students.
When I was in high school a decade ago the internet was just starting to become mainstream. We used it like any other information resource. Kids today however are turning to the internet for all their questions. Google has become the new Orace of Delphi to them. The internet is not in and of itself bad, but the way kids are using it and not retaining information definitely is.
Obviously, anybody can get lost on the internet with more free pornography and video games than any one person can explore in one lifetime. That's a danger for students as well as everybody else. But, the internet is ultimately helpful to students, it gives them a database of information greater than any student had prior to the internet being at their fingertips.
Using the internet is not harmful to student as long as it's used in a positive manner. The internet is a great source for research and getting homework completed quicker. The times that we live in now are technologically enforced. We are looking to make things quicker and easier. The internet does this for many people.