That's just a stupid choice made by (so many) web developers. I checked a sampling of my own sites with Google's tool and they all passed as mobile friendly, but none of them disable zooming. (HN fails, of course.)
javascript:m=document.querySelector('meta%5Bname=viewport%5D');m.content=m.content.replace(/.*(width=%5B%5E,%5D+).*/,%22$1,maximum-scale=10,minimum-scale=0.1,user-scalable=1%22);
javascript:m=document.querySelector('meta%5Bname=viewport%5D');m.content=%22width=1024,maximum-scale=10,minimum-scale=0.1,user-scalable=1%22;HM doesn't disable zoom, it just displays in a teeny tiny font.
Sometimes it's stupid, sometimes not. Disabling zoom removes the 300ms delay added to most interactions on mobile devices [1]. You can alternatively use fastclick.js [2] or swiftclick.js [3], but that's an extra lib/http request to load.
[1] http://updates.html5rocks.com/2013/12/300ms-tap-delay-gone-a...
<meta name="viewport" content="width=device-width">
FF says this issue is "RESOLVED FIXED", so maybe they implemented it too:
https://bugzilla.mozilla.org/show_bug.cgi?id=941995
I have that meta tag on all my sites and I just tested on Android and iOS: Clicking on links and other controls seem instant. And zoom works. Hurray!
"<meta name="viewport" content="width=device-width">"
EDIT: Actually I also include the initial-scale as in the comment below.
<meta name="viewport" content="width=device-width, initial-scale=1.0">I know only lip-service is paid towards accessibility but zoom shouldn't be able to be disabled except by the user.
Maybe my phone is just a little zealous with the zooming, but it loves to zoom into the top-left corner of the textarea. The first thing I do uses three pinches' worth to zoom back out, and if I ever have to move the cursor and thus touch into the textarea again, it zooms in again.
I've always been a fan of moving mobile web towards the standards and behaviors of native apps which generally did not require zooming to get tasks done.
Generally I welcome it, because I can click on the teeeny input field and have it come "closer" to me for editing then get out of the way.
I think with ios 8 this has changed.
Due to that low screen real estate there is an extreme amount of scrolling down, whenever you need that header to navigate you end up needing to scroll a long way to the top.
Links from the bottom are easily forgotten about when you're half or 80% of the way through an article. Likewise follow you around widgets are a painful annoyance 100% of the time.
I still find that very annoying. Sometimes I have to scroll up and find that damn thing covering part of my screen again.
Fortunately I have a bookmarklet that zaps all the position:fixed elements to static :) It works brilliantly in 99.9% of the cases :)