They say it won't prevent you from finishing the game, but what else is there if one person decides to suddenly just make every faction encountered hostile ruining the game completely? of course there is saving and loading.
The thing is initiating the dialogue with the wrong character is hardly an issue if they had done something similar to how Baldurs Gate approached this, by having the dialogue options include the most suited person/suited tag for each choice engaging it as a party(when everyone is present) rather than having to follow the host. There are pros and cons, the thing is hypothetically if you talk with a character by accident that would lets say in almost every scenario lead to making that NPC hostile then the others affiliation to that specific NPC wont matter at all. There are plenty of cases where you can talk someone down from being hostile, then another party member comes up to them re-engages them in dialogue then says things to make them go hostile.
Right now you also got the abuse of when there is a dialogue and its set so that it will end in combat no matter what the three others can kill him while the other one still is talking to whatever NPC allowing for easy kill(obviously a bug, then again the game will have alot of NPCs and encounters).
This is still Early Access and Early Alpha, and I am just stating the issues that are there right now(not that I would ever play with random people on the released game anyway).
I still love this game even as it is, as I've mentioned Ive played through it quite a few times doing things in alot of different ways(already gotten my moneys worth as I've spent more time one the first playthrough than I've spent on many other less engaging RPGs on their playthroughs).
Besides LOTS of things that are still to be implemented for final release, all the other chapters on release, undead hero, chatting with your companions in SP, 2 skill trees, more skills, more traits etc Game Master mode, modding tools. so YEAH.