There's been plenty of debate about whether being kinky "counts" as a sexual orientation. On the one hand, it's possible for a person to be kinky but heterosexual, in which case they likely experience at least some of the systemic benefits of straightness – and kinky people aren't usually subjected to violence or exclusion from society for being kinky, the way many queer people are.
On the other hand, there is mounting evidence that one's kinks can be a fixed identity akin to sexual orientation – and many kinky people do indeed experience discrimination and stigma as a direct result of being kinky.
It's difficult to say definitively whether kink is a sexual orientation, but anyone familiar with both kinksters and queer folks will have noticed some similarities between the two groups. Most notably:
1. Kinky people and queer people are both prone to shame and self-judgment about their desires, because of the sociocultural stigma faced by both of these groups. It's common for people in both camps to take longer to realize what they want, and go after it, than the average straight vanilla person.
Some people's shame is so intense that they may never fully come to grips with their sexuality – although this is likely less common now than it was in time periods when queerness and kink were far more widely stigmatized.
2. Kinky people and queer people both have sexualities which deviate from the traditional "script" of what sex "should" be, and so people of both groups must be excellent sexual communicators in order to get their needs met. You can't, for example, assume that the average queer hookup will involve a penis going into a vagina, or that the average kinky encounter will involve genital contact at all – unlike heterosexual vanilla sex, which many people assume will involve the same general progression of events every time.
To be fair, this reliance on sexual scripts is damaging for vanilla straight people too! We all deserve a sexuality built around what we actually want, not just what society tells us we should want – and queer people and kinksters are at the forefront of the fight for that model of sexuality.
3. When it comes to sex, health and safety are often priorities for queer people and kinky people alike. While straight vanilla people also have to worry about things like STIs and potential pregnancy, the AIDS crisis of the '80s and '90s made sexual health an especially important issue in the queer community. This makes sense given that some forms of sex often associated with queer people (e.g. anal sex) are higher-risk and are often left out of traditional sex education curricula – but it's important to note that straight people can and do have sex in risky ways too, and they would do well to adopt the same safety practices many conscientious queer folks prioritize. These include everything from using lube and dental dams, to discussing your STI status prior to hooking up, to getting tested every 3-6 months.
Ethical kinksters also tend to care a great deal about staying safe when they have sex, although those practices may look different from traditional sexual health tactics. Kinky people may, for example, take first aid classes to learn what to do if a breath-play scene goes awry, or may keep safety shears at the ready in case of a bondage emergency.
4. Many kinky people are queer, and many queer people are kinky. There is a great deal of overlap between these two groups, both currently and historically. The fight for sexual freedom is important to both these groups, so it makes sense that they've often backed each other up on the battlefield.
Kinksters and queers have both been called "perverts" by closed-minded bigots throughout history, and their activities have been conflated in bad faith with crimes like rape and pedophilia. While some queer people distance themselves ideologically from kinksters in order to avoid these damning comparisons, many see kinksters as their natural allies rather than their enemies. These folks understand that true sexual freedom must be sexual freedom for all: straight people and queer people, vanilla people and kinky people, allosexual and asexual people, and everyone else. Anything less than that is not true freedom at all.