Some users use virtual desktops and some activities and some both. the good thing is, that when you use only one virtual desktop and one activity the UI don't show you stuff for VD or activity users. so no move to activity 1, ... when you right click on the desktop you get run command ... activities ... so if you have only one activity you don't need the activity browser. please show this only if you have more than one activity. Reproducible: Always
The activity switcher is also used for creating activities, so -1 from me.
The only place where it makes sense hiding it is if you have one activity and add_activities is restricted through kiosk. Not sure if it's worth it complicating the code for a corner case.
https://techbase.kde.org/Projects/Usability/HIG/ContextMenu * Disable menu items that don't apply to the current context, instead of removing them. * Hide menu items completely if they are permanently unavailable on the user's system (e.g. due to missing hardware capabilities or missing optional dependencies). The background of these guidelines is that users aren't aware of hidden features. It may be clear for expert users, but novices who never heard about a function and don't see how to interact with it will not become familiar with the underlying concept. So -1 from my side as well.
thanks for the discussion and the clear rules. I think I can close the bug report.