A few months ago, my then-roommate ("S") and I decided to try out an escape-room place in our local mall. We arrived on time, but the place was closed, and no one would answer the phone. Eventually, we learned that an employee had gotten sick at the last minute, leaving no one to run the escape rooms during the time "S" and I had available. The manager (or whoever was calling to explain the situation) apologized and offered us a free game to make up for it.
Good customer service, right?
A few weeks later, "S" and I decided to redeem said free game. After a bit of a hassle trying to persuade the employee on duty, "J," that we did indeed have a free game (note to self: make sure to get such offers in writing from now on), we got started. "J" said he'd come back to check on us in five minutes in case we hadn't found the first clue by then.
By minute 17, we hadn't seen hide or hair of the first clue or of "J." We had to use the room's iPad to get his attention. 🙄 He got us on the right track and left again.
Then we got stuck again and had to summon "J" back. This time, he had a cheat-sheet book with him. Despite that--and his assurances that he'd played all the rooms in the store--he couldn't seem to figure out what we should do next. He kept asking about things we'd already done or found. It seemed to take forever until we could get going again.
Did I mention that the air conditioning also didn't seem to be working? In July? In North Carolina?
"S" and I did eventually solve the room, but we both were glad that we hadn't paid for that experience. 0/10 would not recommend.
The reason we didn't have a good experience is also a major reason why people stop reading a book or article: the company/writer didn't deliver on its promises. This escape-room place promised a fun adventure. What "S" and I got was a hot, sweaty, frustrating wrangle.
Similarly, if your writing hints at a complex mystery and then delivers an easy solution, or if it states that it'll prove a certain thesis and then offers insufficient evidence, readers are going to get frustrated. They'll feel that you've raised false expectations and, therefore, wasted their time. And angry readers talk. Whether that's in online rants or negative comments in conversation, their disappointment leads to fewer readers for you.
So what's the solution? Make sure you deliver on what your writing promises. To quote Anton Chekhov:
"Remove everything that has no relevance to the story [or whatever you're writing]. If you say in the first chapter that there is a rifle hanging on the wall, in the second or third chapter it absolutely must go off. If it's not going to be fired, it shouldn't be hanging there."