I slightly disagree with this, in the sense that this would reduce the level of variety in the game. If we could go after any and all precursor chains then our spawning location wouldn't matter so much in terms of the chain, and that is what makes the whole thing interesting in my opinion.I also agree locking player into one precursor chain may not be a good idea. There is no reason why a player should not have access to all five chains, especially considering the fact that he can have open access to all five home systems after all.
Although I will agree that there's no reason why the history of the old galaxy shouldn't be accessible to the player in some way. I'm surprised the devs haven't gone into more depth with this, having multiple nations working together (or competing against one-another) to discover the ancient history of the galaxy and potentially benefit from that knowledge or even rewrite history in their favor.