They were being snarky about a comment when they literally didn't read the entire sentences they were being snarky about. No, I don't think I was unnecessarily harsh.
I had the same issue. I figured it out before I'd have commented similarly, but I completely understand where the confusion came from and I don't attribute it to your reading skills.
> but the first half was so good and original I'd recommend it just for that
Attension span so short you couldn't even make it to the second half of the sentence before dismissing it