Yeah that is true. I personaly have the problem that i do know all those things, and its more in the way that the character should have know seeing the background he/she has.
As a player who has played FO1 and 2 i know what the NCR is, but you are right that someone who only played FO3, would not know what the NCR is, or how they were formed. I understand the need to retell some history or lore for those who dont know it. I guess with FO4 main character living in or around boston might mean he should potentialy know things about its pre-war history, but i as a player dont know that history, so i do expect it to be in their for the sake of me and others who dont know it.
Now just to make it more clear what my argument is, cause i understand the above might confuse it.
I find it strange, and sometimes immersion breaking, that information a character should natively have is not present to him/her. But i do understand the reason behind it is to give that info to those who are unaware of it.
The more anoying i find are seperate topics in a conversation that dont referance earlier topics you discused. Let's take veronica from FNV for a second.
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Say i take my character to the BOS in hiden valley and run throught their queest before meeting her, i now as a character know of their excistance. I go meet her and she ask wether i know them (BoS) and what i think of them. I can litterly tell her i met them and think there ok. Yet later she reveals she is a BoS herself, and then ask wether i still want her to join me.
Basicly the first part of my conversation with her regarding my disposition towards the BoS is ignored/forgoten by her, and then she asks in a generic way sugjesting i was not to fond of them wether i still like her to join me. This is what i mean with a break in conversations not remembering earlier topics discussed.
Rather then forcing the standard talk of her joining me, they could have change the whole direction of that conversation so she would reveal her allignement with the BoS and then just offer to go with me as a companion. (ie: ommiting the whole "sorry i lied" to you stuff.
Now this isnt a big thing, and can easily be ignored, it just never felt like the conversations in FNV flowed well for me, to manny time a NPC asked about a topic, would iignore previous comments in favor of pre-scripted dialog trees.