Very valid points. There are many who look forward to a "punishment", perhaps using that term to define a spanking or something else they are seeking. However, being totally literal and anal sometimes - yes, I know, I am - using the word "punishment" doesn't work for me.

For me, it's simple.

A punishment should be something the person doesn't like.

A reward is something they do like.

For example:

I wouldn't ever reward a pain slut with pain. Heck, I might make them write an essay, take away their toys, or other things that would be considered a "real" punishment. If I was feeling particularly mean, they may be forced to watch someone else get the type of play that they wish they were experiencing.

I would however reward a pain slut with a spanking or other form of pain for good behavior or our mutual pleasure.

Another example:

If my sub was a gamer, I may punish them by taking away their games. (No electronics for a set period of time.)
Ouch!
(This punishment actually works well for my teen boys.)

That said:

There are many couples here on the forums, that use the word "punishment" to mean or describe their play time together. "I was such a naughty boy/girl, master punished me last night and I loved it!!!" Yet, there is no actual punishment involved as they are both enjoying whatever activity they have chosen.