It seems that we agree on the rules, and disagree on how to describe the abstract principles these rules are based on.
(Where are the lawyers when we need them? Smartass kitten? Do you perhaps have a definition of power in a social relationship to hand?)


Anyway, the opening article in this thread has the great merit of pointing out what deplorably enough too often goes unnoticed: What the submissive party can decide and do.
Perhaps it does the discussion no harm to point out the complementary facts. They are less intriguing, because they are rather obvious: What the dominant party can decide and do.

The submissive has to be willing.
The dominant, too.
Story of all those experimenting people who asked someone to tie them up for sexual play and got a refusal, and went on looking for someone who would.

The submissive is allowed to say no, and set limits.
The dominant, too.
If, for example, the submissive wants to try out a type of play the dominant is too uncomfortable with, the dominant is not under an obligation to do it.

The submissive can interrupt or stop a scene.
The dominant, too.
If the dominant party feels that a time-out is needed, or the scene is going into an unfortunate direction, the dominant can call a hold, too. Just does not use a safeword for it.

The submissive is always free to end the relationship and move on.
The dominant, too.
Though some seem to choose the rather cowardly option of withdrawing into silence, or provoking an unpleasant scene, and leave it to the other to formally state that the relationship is over! :yuck:

So I agree that it is all based on compromise and free agreement between free people.
From my point of view, that is so because there is no power involved.


Sources of power
Factual power in a social relationship can come from various different sources.
Legal power. Political power. Economic power. Status difference in an authoritarian, hierarchical context. Fear. Structural violence. Physical violence. Threats. Blackmail. And lots of other things. Frequently exploited for sexual gain in reality.
We also find these alluring power themes in erotic fiction, along with various fantasy power sources such as mind control.
What they all have in common is that, as soon as there is a power difference between real people or between fictional characters, there can be no free consent between them. If one party has power over the other, it is not consent, it is coercion.


Something that has not really been discussed in this thread yet:

'I need you' as a 'source of power'
It may seem appealing to bring the power factor 'I need you so much, I can not be happy without you' into play. It may be an intoxicating sensation to feel desperately needed. Someone who thinks 'I can not be happy without you, but you could be happy without me' might perceive the other's option to leave as a factual source of power. Does this occur in reality? Does someone believe, or remember believing in earnest 'I can not be happy without you'? Then this 'power factor' might be worth further discussion.

In my opinion, being part of a happy relationship is being one of someone's causes of happiness of choice. Not someone's only chance of happiness. Personally, I would not believe someone who in earnest tried to convince me that he/she could not be happy without me. I can't make anyone happy. I can offer sources of happiness. In specific terms, I believe that my partner could be happy without me, and I could be happy without him.

But if someone believes that their happiness depends on the other, the option to leave might be interpreted as a power factor.

Separation hurts terribly, but the hurt does not last forever. If there is a very serious compatibility problem between two people, they can not have a happy relationship anyway, try as they might. And, as mentioned above, de facto both parties always have the option to leave. So personally, I do not see the option to end a relationship as a factual source of power of one party over the other.

Perhaps there is some food for discussion here?


Practical relevance?
It does not seem to make that much practical difference how one formulates the abstract basis of the rules. (Though I really wish someone could help the discussion with a definition of 'power'.)
'Everything is always subject to the submissive's agreement, because the submissive ultimately holds the power in our relationship.'

I would formulate it like this:
'Everything is always subject to the submissive's agreement, because nobody holds any power in our relationship.'