That completely makes sense and I can see that being the use case sometimes. I was just generalizing that in most cases, I think user specific columns wouldn’t be needed if a user is creating a new row. But of course, that doesn’t cover all cases as you mentioned above.
I think it comes down to being largely a technical limitation. User specific columns require a row id so an underlying hidden relation can be created to a separate underlying hidden table (containing row id, user email, and column value) to store those user specific values and properly link it back to the correct row. When you are in a form screen, you don’t have a row yet, and thus you don’t have a row id that’s assigned yet. Because of that, a user specific column value would be left in limbo because it would not be attached to a specific row and wouldn’t have a way to to connect back to the new row which doesn’t get a row id assigned until it’s submitted and saved to the table.
I’m guessing glide would have to rework the entire row id assignment process as well as maybe the user specific column process just to make user specic columns available in a form.