Yeah, it's becoming angry at the author not from an immediate/first reading reaction, as many of the Slytherfen ("What? I like Snape better!") did, but a slower and finer process of disillusionment based on disappointment and different priorities.

Side comment: HP has been so fascinating to me because I've gotten to watch people read a work in progress where the ending makes sense to me, but I didn't predict the direction it went from the middle. Almost no one got the tone of OotP right, going by both meta and fanfic predictions over that three-year gap. I think the process of trying to Figure It Out From What We Have really made him and others snap.