Default interface: can you play it?

I was watching some videos where some prefer the default interface, without any addons of any kind, both in pve and pvp.
There's the frame of the player and the target at the top left and then there are the buffs and debuffs of the player at the top right.

They probably constantly look on every part of the monitor to check what's going on, in pvp especially . Now they look up to the left, then to the right, then to the center, then to the target which is obviously not still, it moves.

Maybe they are now used to playing like this, but if I had to try I think I would only get a headache.
How do you play?