What is a proper development concept behind multiplayer?

There's so many ways one could manage it. One of these is:
Have 10 players in the game, have 9 players send their input to game host, have host verify tokens and security, which is 9 internet inputs and 1 local input. Host's Unity, constantly executes commands in game's scene, and accurate updates are being sent to every player every 20ms.

I never really developed such a system, what is a general consensus on frameworks regarding a multiplayer game?

 

I'm no expert but I'd say it's really dependent on how your game works, your expectations in terms of performance / reliance on good ping and how you want to have the shared data processed (whether it be through a central dedicated server or a peer to peer host). I don't think, therefore, that there is such a thing as a "general consensus" on the framework - if there was someone would have developped the ultimate networking engine that you could plug into any project and making online games would be a whole lot easier.