I get these sort of criticisms a lot and I see it given to others a lot as well. I personally think it's unreasonable criticism because what you've been given is an out of context half-chapter, clearly well after the characters, settings, factions, politics and world have been established. For all you know this is the second last chapter and yet you demand to know all the context from this half chapter.
What am I to do? Put foot notes on every second page with constant updates on pre-established information? It's unreasonable.
Imagine picking up The Lord of the Rings books, flicking to the final battle by the Black Gate and then calling Tolkien out for not making you invested in the story, so you put it down?
Not to sound indignant, I've just heard the same thing over and over. I show people my most proof read section as a best example of my writing, not to get them invested in the story, especially because that's not where the story starts, not even close.