I think this is part of the underlying problem.
From a technical/medical/scientific perspective, sexual orientation is very very vague. We can make some generalizations about it, but it still doesn't seem to look the same in everyone, it can shift, there seem to be some cultural elements, we don't really have much idea what causes it, there is no marker you can measure, we know sometimes people have sex with those supposedly outside their orientation for all kinds of reasons, and there are wide differernces in how individuals describe and explain their own sexuality.
Given all that, had do we separate what we think of as sexuality from other things like asexuality, or sexual attraction that targets other charachteristics?
Back in the 80s, there were people who made the argument that if we started defining sexuality in the law around what people are, rather than what they do, it was going to cause problems. I think this is certainly part of why we now see that groups like Stonewall are primarily identity movements and behave as identity movements, right down to mandating political views.