There should be an option for a very rich-text column type (formatted text, links, images…), but WITHOUT user access to other doc data.
The use case is writing reports or submitting assignments and such, in a shared doc. With some hidden pages containing other reports from other users and various information not needed by other users. Yet, in canvas columns, if they hit / or =, everything is offered to anyone.
I need them to be allowed to edit the content of the canvas field in their assigned row, including inserting images etc., but without this simple access to read (and edit) other stuff. That is no inserting tables, views, canvas formulas etc.
A simple (from my point of view ) checkbox in column options would do.
(I do realize this does not guarantee any security and there are other ways, this one is just too straightforward and already caused us some pain, even without any bad intentions by anyone, they just went exploring.)