Because the search is a total piece of crap and doesn't do three-character words. It's also why you can't find anything about the infamous "CPS", or find out why your "A/C" isn't working, or who's running "ARB" ...
It won't even let you search a 9 character phrase made of 3 character words "old man emu" in quotes.
Since most people get their OME from Dirk or Jason, you might try searching for "dirk", "jason", "jeepin". "dpgoffroad" (but not, of course, dpg) and then manually weeding out the results.
You might also try jeepsunlimited.com