I downvoted you because you've repeatedly complained about the same thing on several stories for a while now. Pinch zoom gets disabled to remove the 300ms delay on mobile-friendly pages, and that's seems to be what most people want.
If you always want pinch zoom, I would suggest using Chrome -- there's an accessibility option that overrides the page's request to disable pinch zoom .
To re-enable zoom. I get as annoyed as the the parent comment with sites that disable zooming not because of the act itself but the bad design and typography choices that seem to go along with it. Make text size and leading choices suitable for the device, set margins so that your text doesn't abut the absolute edge of the screen, and make sure links are large enough to tap reliably. If you feel you can't make those choices and want to include full site or text size links somewhere then they should be obvious and again big enough to tap.
I upvoted the earlier comment because something interesting is worth repeating. I wasn't aware of the issue or your explanation, so good thing he/she posted in the first place.
I am using Chrome on iOS and I do not see such a setting. Furthermore, I fail to see the advantage of 0 delay on a mostly textual page. Based on the upvotes many agree with me.
If you always want pinch zoom, I would suggest using Chrome -- there's an accessibility option that overrides the page's request to disable pinch zoom .