Sad thing is, sometimes infodumps in a story have to happen. Sometimes there’s just information a particular character – and the reader – has to have to fully understand the magnitude of that giant space rock about to drop on everyone’s heads.
But they can be annoying. And obvious. And too much like a class lecture – and who reads a class lecture for fun?
…Well, I’m sure someone out there does. But if people wanted a class, they’d probably go sign up for one. They picked up a book, which means they want a story.
Still, no matter how many drawbacks they have, infodumps in a rough draft can be critical for the writer.
Because there’s always. Always. Some little fillip of your world/monster/magic system that you didn’t figure out before you started. And sometimes the only way to figure it out is to write it out on the page.
So. Infodumps in a rough draft? Yes, put them in there. This is NaNo; write everything, no matter how clunky, as fast as you can! The time to edit will be later.
Later, though – then we all get to see what we can cut, what has to stay in for things to make sense, and what can be repurposed and scattered in later (or earlier!) bits of the story. So that our characters aren’t launching into a long and academic diatribe on How Do You Kill X Demon in the middle of a chase scene.
…Unless you have a TARDIS and are playing with the space-time continuum anyway. In which case, I salute you, better you than me. Time travel gives me such a headache.
(Or so my future self supposedly says. Is Future-Me always so scary?)