The issue Ladyofdragons is referring to is called "concurrent updates".
If two persons are changing the same data "object" in the database at the same time, ONE of them is going to lose his/her work.
All of the means of allowing this kind of thing would require constant on-line access to the shared data.. in order to coordinate who is making changes at any given time, only one user can have "write" access, and all others must wait for that user to finish, commit his/her changes, and release "write" access to others.
The alternatives are things like lost updates. The Player makes a note on the Topic, and syncs to the server. Then the GM makes a change to the same Topic using the version the player started with (before the player's changes), then syncs. The GM's changes replace those of the player, and the change the player made is lost. The player, and anyone else who sync'd after the player but before the GM, would see the player's changed version.. until they sync after the GM's changes are sync'd, and then everyone sees the GM's data.
Otherwise, if the GM's data doesn't "rule the roost", the varying saves of the data by various players could each replace the GM's and each others... especially bad if multiple players made changes building on each other while the GM was preparing changes ... then a series, almost a conversation, of changes, get wiped out.
So the way to prevent that kind of crazy confusion is to allow NO ONE other than the GM to make changes to Realm Content.
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I am speaking as someone who has designed, built, and operated a database application managing multiple users making changes concurrently. As soon as you start allowing more than one person to edit a piece of data, you guarantee that some of them will be getting a message "your changes could not be saved because another change has already been made", or that some changes get wiped out in favor of others. Since neither of those is good for the product , LoneWolf has (has far) chosen the safer course of allowing ONLY the GM to make changes.