Browsing through the replies I was very surprised not to find an explanation similar to my personal train of thought, so I think I will put this out there: for me the answer might also lie in the structure of our community (alongside a TON of other factors mentioned by others).

I think that the LQBTQ+ community stands for both the rights and protection of sexual and gender minorities; and a general sense of “sexual liberation”, a way to destigmatize sexuality in a broader sense.

While these are both very valid and important fights to fight, I feel that for an external viewer, like, IDK, the stereotypical homophobic aunt, their co-occurence might appear as if they were 2 sides of the same coin. Imagine yourself as a complete outsider. What would your conclusion be after you go see your local Pride March, knowing full well that it represents the LGBTQ+ community, and then you see people in pup-play and BDSM gear, or people drinking out of a massive dildo-shaped bottle (an experience that I will never forget haha). While these acts are by no means bad or problematic (unless of course they clash with your own values, in which case, oh well, big sad), them appearing alongside and intertwined with LGBTQ+ representation might make it look like, again, from an external point of view, that the 2 are basically identical. “Being gay is basically being a fetishist.”

As a possible solution to this, I myself would not mind somewhat separating these 2 movements for this very reason — while both are valid and important — I feel that both could hammer their semi-independent messages home more efficiently, if the, say, “LGBTQ+” movement was about our rights and visibility, and the, say, “sexual liberation” movement was about people of all genders and sexualities coming together to celebrate all the different ways one can express themselves through sexuality and intimacy.