Why UE4 havent sceneview camera?

Like in Unity3D.
Its usefull.To see on smtnk on scene in runtime.

Actually, it has.

You can press G to toggle Game View, which hides all the gizmos. Also, you can select your camera (or place another one) and pin the realtime render from that camera to a corner of your viewport.

These are different things.
When i press play in UE4, i loose sceneview camera controll. And it becomes gameview camera. I cant fly around the scene and so on.
In Unity, i can do in runtime witch sceneview camera same things? that i do in editor mode. I have controll, i see gizmos, hiden volumes and nonrender objects, and I can look at what is happening on the part of

Instead of “play” use the “simulate” mode.

But what to do if i write custome camera controller and i need to check how it works in my snene? Or i see something not clear. With sceneview camera i can see that gameview camera with my controller looks wrong, or in wrong place. Useful for debug.