Graham Nelson

Players will try to talk to every human character in the game and complain they don't respond to most prompts, not realizing how much it takes to implement.

As Graham Nelson's book Informed Designer's Manual mentions in the design of puzzles section, the woman selling breadcrumbs in Infocom's Trinity has over 50 different lines, and, you know, the only thing you actually need from her is to buy breadcrumbs before you both get nuked.

But the developers anticipated that the player will ask her about every item in their pockets and everything in the park around them.

And Adam Cadre's Varicella from 1999, a game of courtly intrigue, has 450 flags dedicated simply to tracking about which subjects you have talked to which characters so that repeat questions don't play out the same as the first.