Doing something that inconveniences or irritates people gets you griped at.
A greasemonkey script wouldn't "advocate" anything; its use would be the (admittedly reasonable) action of someone not waiting for everyone else to get a clue and do something right.
The browser defaults for outline are ugly, that's why so many people set outline to none. So, some visual examples that show sexy outline stylings seems a more reasonable approach.
The author dismisses all aesthetic concerns and loses credibility with the aesthetically minded people he's trying to convince.
A greasemonkey script wouldn't "advocate" anything; its use would be the (admittedly reasonable) action of someone not waiting for everyone else to get a clue and do something right.