This is true, but only if you don’t use permissions. In the realm world the user only has access their own data - if you have shared data then yes, it will be available.
But that will be available if i create a simple account for your app too…
So as I understood, given a cloud istance url, everybody could connect to it as a registered user and make what he wants. It sounds very strange to me, so maybe something isn’t clear to me.
Thats true for every database. Why is it a problem, that everyone can register? Doest it matter that they do it in your app or vie script?
What’s the point of have username/password if everyone can get one? Only to register identities?
This is the goal of everbody-s application, to reach out users that can create an account an use the services. Why would you make limitations?
Do you want to have paid tiers in your app? Then have a free one with limitation and make your own logic to have premium features.