Except sometimes you want or require a physical book... not all books on the internet are available freely, legally. Also, libraries offer free access to the internet, computers, printers, etc, which (believe it or not) not everyone can afford.
If it were true that the purpose of public libraries had been superseded by the internet then no one would be using public libraries, and they would all have closed by now due to lack of funding or public interest. That public libraries continue to exist, and that people continue to use them, suggests otherwise.
If it were true that the purpose of public libraries had been superseded by the internet then no one would be using public libraries, and they would all have closed by now due to lack of funding or public interest. That public libraries continue to exist, and that people continue to use them, suggests otherwise.