Comment by lukan

"My first guess would be replicaton isn't that critical, because a user would mostly interact with an instance that's nearby, and this instance has their data. But the page mentions"

Apparently not

"Each account is associated with a DC upon registration and does not change with the user’s phone number or geographic location. Users cannot freely choose a DC—if connected to the wrong DC, the server returns an error message, requiring the client to connect to the correct DC associated with the account."

according to this source: https://news.ycombinator.com/item?id=48920475