Don't disable pinch to zoom
… As all the other options are nowhere near as usable:
1) iOS native zoom (eg zooming the whole screen) does not understand text structure. You cannot zoom into blocks of text automatically. The inability to zoom into text blocks renders the iOS screen zoom an almost unusable experience on the web.
2) One size does not fit all. Not everyone can read 12px text. Rotating the phone to act as a zoom is easy, fast and effective.
Rarely things are absolute, I’m sure there are sensible edge cases, but keeping zoom enabled is a sensible default.
In the BBC mobile accessibility guidelines disabling platform accessibility features (such as pinch to zoom) is prohibited, we think this is a sensible starting position. If you disagree, please contact us, if you have tested this please share your results.
And that’s about it.