I don't really agree those are the only reasons. We keep as much of our logic on the server as possible - partly for the reasons you state, but also because -

I don't really agree those are the only reasons. We keep as much of our logic on the server as possible - partly for the reasons you state, but also because - as a team, we generally prefer working in C# to JS - there's benefit to having all your business logic in one place. It's easier to concentrate it in the back end than in the front end - minor: we can roll back our server instantly, rolling back our client requires a user page refresh