Asexual people are fully present in BDSM communities and have been for as long as the communities have existed. BDSM encompasses power exchange, sensation, psychology, and connection, none of which require sexual attraction as a prerequisite. The community is more varied in how people relate to sex than popular representations suggest.
The assumption that BDSM is primarily about sex, and therefore that asexual people are anomalous within it, misunderstands what BDSM actually contains. Power exchange, dominance, submission, sensation play, bondage, and psychological intensity are distinct from sexual activity and can be pursued by people for whom sexual attraction is absent or minimal.
Many asexual people engage with BDSM because they experience erotic interest, aesthetic pleasure, or psychological satisfaction from dynamics and sensation that does not translate into sexual attraction in the conventional sense. The distinction between erotic interest and sexual attraction is well-established within both ace community writing and sexuality research. Asexual people can have erotic responses, enjoy physical sensation, and desire intimacy while not experiencing sexual attraction.
Others engage with BDSM specifically through the relational and psychological dimensions: the structure of a power exchange dynamic, the trust and care involved in submission or dominance, the psychological intensity of certain types of scenes, none of which require the scene to conclude with or center on sexual activity.
In practice, ace people in BDSM communities sometimes need to communicate their limits around sexual contact more explicitly than they would like to, because assumptions exist. Negotiation that specifies what the scene does and does not include is important for everyone and particularly useful for aces. Some community spaces and events are explicitly sex-optional or sex-free, which some ace practitioners find more comfortable.
You belong in this community if BDSM interests speak to something in your experience, regardless of whether that experience is organized around sexual attraction. The community is not a monolith and contains considerably more variation in how people relate to sex than its cultural image implies.