Why not a skeletal mesh for mirror than all that extensive vector math and screen capture ..?

Hi everyone.
I see all these amazing tutorials on You Tube on how to create a mirror in Unreal 4. Using vector math and screen capture in BP.

Why all that trouble if you can just create a skeletal mesh that captures its own reflections?

I mean just cheat and make the mirror mesh not static but skeletal?

Did this quick test added skel mesh with 100% reflective material under the plane to see if I can get reflection in water or ice effect. This might work but I can see why it wont work for a mirror where you need a 100% reflection.

730_Testingreflectionplane.jpg

Planar reflection actors? https://www.youtube.com/watch?v=mGunnkDsEio

Planar reflection actor on a disc.