It’s a matter of courtesy, Philster. Ett-kit. 
It’s just the convention on this board. I kind of dig it – it’s considerate.
As far as the bold on first mention that USCDiver brings up, I assume it’s a holdover from the old society pages from which these “Sportsbeat,” “Celeb-beat” and “Metrobeat”-type columns evolved. It’s the standard style for society pages/gossip columns.
Sorry, Ringo, but I don’t like the idea of dropping the bolding on the second mention. Posts on the SDMB aren’t a society page; the bolding here is out of etiquette and respect.
–Cliffy
What astro said.
I agree wholeheartedly, Mangetout.
I agree with Ringo, MANGETOUT, and, what the hell, Bruce_Daddy … even though he hasn’t posted in this thread.
Just be thankful the <blink> tag doesn’t work.
Well, me too. And I also agree with sooner!
And I heard that the <blink> tag has been putting in applications! :eek:
(see ya, Later!)
—have missed you all! 
You know, even I don’t do this anymore…
It doesn’t help vanity searches, actually, because when you do one the system highlights the search term for you in red. (Although, come to think of it, I wonder if it’s bold AND red…)
Just red, not bold. (Try it yourself. Just add &highlight=### to the URL, replacing ### with what you want highlighted.)
Well, red alone is sufficient, since the rest of the text is black.
A little quirk noone has yet mentioned: our usernames are, in fact, in bold! Look at the info boxes on the left hand side. “member” – not bold. “Registered: Aug 2000” – not bold. But the username is in bold.
Therefore bolding the username isn’t just convention, it’s actually technically correct!
pan
I disagree.
And damn it, I started this game elsewhere.
You guys realize you’re giving TubaDiva flashbacks of the old AOL days and A Certain Unnamed Poster, don’t you?
For the record, I didn’t do it this time! 