Regarding usernames with numbers in... Never used them[1]. Which:
a) Shows me to be old, because when I started, it was (aside from being pre-web) not common for places to be heavily-subscribed and thus a "norm" that you'd have to choose a numeric add-on to your chosen handle (no matter how obscure the dictionary or near-dictionary word or name you might wish to use) to differentiate yourself from a million others with the same idea,
b) May also show me to be non-populist, as since the great explosion in the Internet's popularity[2] then I've heavily resisted all those popular Web2.0-type places. (Facebook? No. Twitter? No. LinkedIn, Foursquare, Skype, etc.? No, no and no, etc.... Call me a Luddite if you want[4]. You'd be not far wrong.)
(Let's see. Neopets = 1999, Runescape = 2001, AdventureQuest = 2002 (never even heard of that one, thought you meant the 1970s thing, at first...). No, completely missed those crazes, even if I were to know what they are. GameFAQs, which I
have used, within the last decade and a bit on a read-only basis, dates as late 1995; which is pretty ancient, when it comes to the Web (and looked it, being nice pure monospace fonted text documents as befits the technical site that it essentially is, whenever I've checked it out), but occurred during my period of Internet Hiatus when I wasn't regularly connecting to use the matured (and by now 'Eternal September'ed) Usenet or the fledgling Web, but before any
normal person that I knew had any idea about the Web (or Gopher, or FTP or Usenet) or what the "@" symbol even looked like...)
Erm, I might be missing the point of this thread, now... Please ignore that, if I am.
SSooo...
You have multiple usernames for every place you visit?
If that was to me, indeed I generally have a single username for
each place I visit (main exception already foot-noted in OP), but each place I visit pretty much getting its own username (
sometimes to a relevant theme) thus multiple usernames across my whole Internet Presence
(TM). (In fact, while I also tend to use differently formulaic passwords, I do know I actually have identical passwords for non-identical account-names, but none of that being anywhere that it remotely matters, and for far more casual places than I consider this forum to be...)
Not only that, but I tend to register different email addresses (usually from my same I-own-everything domain, but different names before the '@') for every place I need to. Useful to know who is spamming me (or who the spammers pinched my address from), or, at least, lets me quarantine a spammed address (whether or not I change the one that I register with, on the offending site, to see if it's just a one-off thing) so that I can perma-ignore them. Last time I had bother (rare, as I'm not one to fling myself onto
every online place's books, as already described) it was an address I'd used on a Job Hunting site that started to get multiple spams about how to Advertise (probably Spam) My Business Better. Wrong target? Well, certainly in my case.
[1] Chosen names usernames, leastwise, as student accounts for the Unix/VAX/etc servers were department-prefixed and the remainder being a number serially assigned upon demand and recipients had zero say in what they might be...
[2] Way past the Eternal September, and further past the time when you actually started to see these "URL" things on advertising hoardings, and then AOL floppies[3] started coming through the door. Darnit, this is
also making me feel old.
[3] Later, CDs, making much better coasters and could also be made into shiny Christmas decorations.
[4] I've
used Ludd as an identifier, but only for a transient avatar in a Flash game[5]
[5] Two pairs of tanks, side-view, shooting at each other with basic elevation/power control, wind effects and the like. Named identification just there to facilitate the inbuilt chat between the randomly grouped allies/opponents. Been
ages since I've played it, forgotten what it's called or where I'd find it, if it even still exists...