In this Google Webmaster's answer, it is stated that one of the cons of specifying a canonical
link is that it "can add to the size of the page".
I tried searching the web for more information on that topic but most articles I found were quite old and even then there was no mention of an increase in page size due to usage of canonical
link.
Does the author refer to the nominal increase in the page's size due to the extra few lines in the markup? The wording makes it seem the impact is greater than that.