I thought about this potential case afterwards. Need to test. It's likely not very high priority because you have to turn WTE on for your account in preferences, and WTE doesn't work without JS.
|mediawiki/extensions/VisualEditor : master||Move NWE URL changes into JS|
If you're a non-JS user you won't be able to switch on the beta feature, but of course people have different machines so could theoretically enable on one and try to use on another. And of course users occasionally lose JS due to network issues or whatever.