I think there is a need for two distinct types of test cases. One focused on the technical aspect of the changes and one for non-technical individuals.

Even enough witnesses are not enough tech savvy to run successfully some highly technical tests, and asking for help to run them would only waste the time of those who can run these tests successfully.

But non-technical tests I'm sure they can run. If those tests should be the same as the ones for the vast majority of stakeholders, or may include some more restricted areas, they can access from their positions as witnesses, I don't have enough information to know what's better.

But I think there should be differentiated test cases, based on the level of tech expertise and access to certain tools and server setups, and certainly some for the large userbase who understand their role as stakeholders.