The engine is multiplayer first because you don't have to write any special code to implement it. When you start a game, if you set maxplayers to something beyond 1, it's multiplayer automatically.

When you create entities in the engine, all you have to do is specify what fields you want networked, and the game engine automatically serializes deltas for you on that field as they change.

It takes care of more advanced field networking like prediction as well.

You focus on making things, not making them networkable. If you want that, you just say it's networked. That's it.

Maybe you should put that pitch up there on the starting page, because personally I find it too bland. The screenshot doesn't tell me anything, might as well not put it up there.