Sometimes, you may have access to quests giving rewards. However, these rewards may have requirements which are hidden until the moment you actually get it, meaning you may be really disappointed doing the whole quest for nothing.
An example, I saw a weapon with +10 accuracy, and was really interested for my rage character. Did the question, and then noticed once I got the reward that I needed bladed weapon II in order to use it, something I wasn't planning to invest into, and not just for a weapon...
https://i.imgur.com/daCATJF.png
https://i.imgur.com/CNFMBa0.png