I think the opposite meaning of factoid (ie: a small, very specific fact) is actually the more common usage.
I've never heard anyone actually use the original meaning, but frequently hear the "small fact" usage - except to point out the opposite meaning. (I've done some work in question answering, and the "small fact" usage is exclusively the way I've seen it used in that field)
I find that the most common usage is for someone describing what they think is a small, very specific fact, but is in fact just a repetition of an old wives' tale with no veracity whatsoever. So maybe the original definition isn't intentionally used that often, but it does end up being relevant quite a lot!
That’s also the more common usage in my experience, though the -oid suffix (derived from the Greek for “likeness”, cf humanoid/android, spheroid, etc) indicates that the other meaning, “something fact-like but necessarily a fact” is more etymologically correct.
I've never heard anyone actually use the original meaning, but frequently hear the "small fact" usage - except to point out the opposite meaning. (I've done some work in question answering, and the "small fact" usage is exclusively the way I've seen it used in that field)