Memento wants to make it as straightforward to access the Web of the past as it is to access the current Web.
If you know the URI of a Web resource, the technical framework proposed by Memento allows you to see a version of that resource as it existed at some date in the past, by entering that URI in your browser like you always do and by specifying the desired date in a browser plug-in. Or you can actually browse the Web of the past by selecting a date and clicking away. Whatever you land upon will be versions of Web resources as they were around the selected date. Obviously, this will only work if previous versions are available somewhere on the Web. But if they are, and if they are on servers that support the Memento framework, you will get to them.