If I choose to label them "incorrect" for their usage of "factoid", by your own argument I'm absolutely right.

Descriptivists may say yes, but that doesn’t mean people won’t try to stop the meaning drifting to prevent the past becoming inaccessible.

Seems to have happened with "momentarily". Used to mean "for a moment" but now most people use it to mean "in a moment".

I remember being amused the first time a flight attendant said "we'll be taking off momentarily".

It depends which people you are talking to.