Hey Adrian, thank you for sharing your thoughts on this matter. However, it would be unfair to call this an absolute rule. We’re building a web app where the main functionality is chat- the UI looks a bit like Slack or Facebook Messenger on mobile views. It has all the functionality (plus far more) of a standard mobile messenger app.
The main issue with allowing zoom is it can cause a terrible user experience. Mobile browsers like to resize and move the page around whenever the user taps an input field, for example. While it doesn’t break the UI, it means that the user is constantly zooming out after sending a message. It’s totally not what a user would expect or be even remotely pleased with.
So while I agree with you in the respect that the viewport meta tag is over-used (yes, even abused), there are some situations where it does make sense. Remember, the user has accessibility settings built into their OS and browser which will adjust things like font size for them automatically. Anyways, thanks for the post- if anything, it’s reminded me to do some more in-depth accessibility testing and feature building.