In some cases the writer doesn’t care that readers are put off by backstory and exposition. They need to know stuff and the quickest way to tell them, is to just tell them. Sometimes it works for the genre. The lead robber of the bank heist will give the “Let’s go over it one more time...” speech, and it's kind of expected.
Sci-fi geeks want to know how your teleportation device is supposed to work (so they can scoff at your poor understanding of quantum physics). And if the reader is heavily invested enough they’ll even let slide the ridiculous rules to your made-up sport that makes no sense (150 points for catching a snitch? Really?) .
However, assuming you want to work in your backstory/exposition in a subtle and elegant way, there are a number of techniques available to you.