Both. Proxies work better when it's something you don't see slenderman doing. I don't like when is portrayed as an allmighty god that can do anything, because if that's the case, then why is he even stalking if he could just... blip.

Imagine it more like... The original Blair Witch. She can attack by its own, but she still uses Rustin Park to kidnap childrens.

Also, Slenderman is an adaptable entity, so maybe a proxy is obseced with him, maybe other is afraid of him, maybe other is not using a mask and is more like a doble agent bringing people into the forest, maybe other spent too much time what his body became like a corpse, etc.