So say you’re an avid NYTimes reader and you have a subscription. You’re logged into the NYTimes on Safari and reading articles. If you want to save an article as a Web Archive and you use the “Clip to DEVONthink” Safari extension, the extension won’t recognize that you’re logged in. So when it clips to DT, it won’t be the entire article.
If you use the “Web Archive” bookmarklet, it WILL recognized that you’re logged in and will clip the full article.
That’s just one example.