Unfortunately this is wrong. DirectX for instance is left handed. Maya as well
They are conventions. Left or right re both ok and an engine has to stick with a convention.
So no this is NOT unappropriated. This is a convention.
And get ready for more. Even though we were right handed by default, should we pick Y up or Z up? because Max is Y but unreal is Z.
Maya and Unity are different as well.
There is NO truth but only conventions
But for your convenience, as I mentioned earlier, you can still force Babylon.js to be right handed:
scene.useRightHandedSystem = true;