You might be underestimating P(X read that particular XKCD | I know X), as I am a physicist, and know a fair number of engineers and computer scientists and a few mathematicians;
you might be underestimating P(X continued to read enough of the site to stumble on my username | X was led to LW for the first time) -- I've commented a lot, including on many of the posts linked to on the about page and the welcome threads;
it's not motivated doxxing (which I know is very very unlikely) that I'm worried about -- comments which I would mind someone I know in meatspace reading comprise a sizeable minority of all my comments (not just for the consequences to myself -- I'd dislike, as a terminal value, certain people to hear certain things I've said about certain topics, especially other people).
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.