Are you taking the position that spanking is precisely equal in harm to restrictions
No. I think it would be hard to make a meaningful comparison between the two things, and maybe no harm is involved.
There are different levels of spanking, just like there are with restrictions.
At the lowest level, spanking doesn't even cause pain. I'm not sure what the point is, but it exists. At the other end of the spectrum it becomes abuse. The same thing can happen with restrictions.
That said, I have restricted my kids from thing like video games, but I haven't spanked them.
It seems like there can be initiation of force in many different kinds of punishment, not just spanking.