Sexualities generally refer to sexual attraction. Homosexuals are sexually attracted to people have the same gender, not to repeating the same sex acts over and over and heterosexuality is about attraction to people with different genders, not to novelty sex acts. Pansexual does not mean attraction to pans not to literally everyone or everything. Taking the words too literally is not really useful.

The differentiation of the ace/allo axis and the sex-favorable/sex-repulsed axis is particularly useful for aces, but it still has its use for allos as well (some people who have PTSD related to sexual activity may be sex repulsed, but can still experience sexual attraction). Lots of reasons to engage in and enjoy sex other than attraction to a specific person. Even allos often engage in sex with those whom they aren’t attracted to.

The major ace subreddits regularly had issues with sex-favorable people complaining about all the posts being sex-negative and sex-repulsed people (sometime simultaneously) complaining about too much sex-positive content. Would be more amusing if those types of posts didn’t waste so much space…