No, if you innocently view a page on an underpowered server, you are not part of a denial of service attack and are, by definition, innocent. A Denial of Service attack is explicitly malicious.
A Distributed Denial of Service attack can be made up of a bunch of people innocently viewing a page on an underpowered server though. The people clicking on a link don't have to know they are part of an attack, even if the link was made expressly to bring a site down. A link on 4chan or any large website can easily bring down a site, especially if it's to a resource heavy page.
