Despite the heavy usage I it hasn't been canned and I have never heard anyone at work complain about JSON for any reason.
You could say it is network effects but if it were crap you could replace it much more easily than say moving from Python to Java or whatever. Especially for internal microservice stuff and perhaps front end.
JSON and the tooling is basically solid. It is a non-concern.
A random click on a website might not be a great test, but it is a test nonetheless. And if it fails enough times, someone somewhere will be held accountable.