Q. When I want to cite a website from the web, why can I not just copy and paste the address?
In APA style, citations need more than just the website address. Some other publication styles allow for the website address as the in-text citation, but APA does not.
In APA, the authority and currency of the information is of key importance. That is why those two pieces of information are listed first in the reference lists. That is also why those two pieces of information are put in the text of the paper; so your reader knows immediately the name of the author (authority) and the date (currency) of the information. A website address alone does not generally tell us that information. A website address can also be excessively long and difficult to put into a paper without causing it to be less-readable.
If you need more information on how to include a website in your reference list and/or in the text of your paper, please see our Answer on that!