I was recently introduced to MongoDB and going through the installation guide I came to know that we have to first run the daemon (mongod) and then we have to connect to the daemon through mongo.exe (for windows) to actually run the commands. I have noticed this is a general structure for most of the DBMS where we have to start a server and then connect to it to run the commands.
Why can't we run DBMS in a single program instance as we do with Python or Node.js? Specifically, why we need the server-client architecture for a DBMS?