I'm gonna start off by saying that FNV is lightyears ahead of F3 and F4, but its overall quality is ridiculously overrated. I'm replaying the game right now for what is probably the 15th time, and the quest design is, for the most part, extremely linear, save for a few fantastic exceptions. The quests in general are decently good with pretty well written storylines, but let me use the quest "Beyond the Beef" for illustration here on the limited options the game gives you.
The quest's about saving a rich guy's son in a hotel full of cannibals. The son's been kidnapped by the hotel staff, and the father's unaware. First off, the game gives you the direction to "ask around for where he is". You're essentially unable to ask any of the NPCs working for the hotel for any information save for a specific lady. After which, she provides you with information that she shouldn't have, that their society used to eat people. You can then ask the concierge about this and with a speech check, you can convince him that you, too, are a cannibal, at which point he'll outright explicitly tell you that they're holding the guy's son and plan to eat him.
So how does the game respond to this? It simply doesn't. After refusing his quest offer to kidnap someone else to replace the rich guy's son so that they can release him no harm done, I'm not given the option to tell the rich guy that I know exactly where his son is. In fact, I had to go back to the same concierge, and tell him that I'd like to speak to an investigator looking into the disappearances of people, at which point he asks me if I have any business with him or if I have any information pertinent to what he's looking into; this from the same guy who 5 minutes earlier told me they kidnap and eat people.
Anyways, so after "lying" that I had information for the investigator through a speech check, I'm given a key to his room, and upon getting there discover him murdered.