D/s
While D/s resembles traditional marriages under patriarchy to some extent - especially when following older rules that believe that submissives can never have any will of their own - this is not the reason that kink exists.
Kink exists because people have always had attractions that involve power - either having it, or giving it over to someone else - and as a result, kink that involves power exchange will always have the potential to resemble other systems of power, including systems of oppression or abuse.
Heterosexual relationships are likely the most common example of oppression in an intimate relationship, and abuse frequently occurs in them, as abuse involves the presence of power. Therefore, an intimate relationship that involves a power exchange will inherently have things in common with traditional patriarchal marriages, as well as abuse.
We are not of the opinion that this makes kink inherently oppressive or abusive, even if it makes some kinks or some aspects of kink worth questioning and examining. Rather, we are of the opinion that kink is harm reduction for wanting to participate in romance in a society that has the systems of oppression that lead to things like marriage in the first place, or for wanting to be abused because every romantic relationship you have grown up seeing has had abuse in it.
Our system considers our D/s relationships to be a queering of traditional heterosexual relationship roles. Doms and subs are not chosen by their biology, or even their genders. They choose to be these things because they want to be these things, and playing these roles gives satisfaction to the people who identify with them.
Unlike how gender is treated traditionally, someone being a Dom or a sub in our system affects nothing about how people in the system treat them outside of kink, romance, or sex. It is not like how women are treated as subordinate to men even outside of their individual intimate relationships with them.
While some older beliefs about kink see it that submissives should do whatever their Dominants tell them to do, no matter what, our system sees the dynamics of kink as being more flexible than that. Submissives have much more agency in their relationships in our system than they have been encouraged to have in previous times, and more than women are usually considered to have in their relationships with men, especially in bygone eras that our upbringing resembled.
It would probably be better if our system didn't have to emulate heterosexual marriages in order for relationships to feel romantic, but unfortunately, that's the consequence of being raised in the environment we were raised in and not knowing how to meet functional and open gay couples who feel that they are something other than friends having sex with each other. It's nice to have a friend you can have sex with, but for someone who wants romance, it's also nice to have relationships feel romantic.
The concept of romance we were raised with is inaccessible to gay couples, but it's also all we know, and if a relationship isn't like romance as we know it, it doesn't feel romantic. Therefore, kink is the best - and to an extent only - way for our system to make a relationship feel romantic.