When people say that "only a-spec people can use the split attraction model," it makes me think that they don't see a-spec identities as orientations in their own right. They see it as a lack of orientation.
If you can be (for example) asexual/biromantic or aromantic/bisexual (which, you can), then that inherently means that you can have a sexual orientation separate from your romantic orientation. Asexual and biromantic are two separate orientations. Aromantic and bisexual are two separate orientations. Asexual and aromantic are orientations in their own right.
If you think that this split in orientation is a-spec exclusive, your conclusion only makes sense if you don't consider ace and aro to be orientations in their own right. Otherwise, what exactly makes ace and aro different than other orientations? Why would an a-spec person be capable of experiencing split attraction, but not an exclusively allo person?
If your answer is something along the lines of, "well, ace and aro means no attraction, so it's okay, because it doesn't cause any conflict with the other orientation" ... You have proven my point. You're conflating "no attraction" with "no orientation," whether you're doing so consciously or not. Asexual and aromantic are not an emptiness or a blank slate. Supporting a-spec people necessitates supporting the split attraction model, whether it's used in an a-spec context or not.
One of the things I've seen people say is, "Allo* people who use the split attraction model are just experiencing comphet/internalized homophobia/internalized biphobia. They're just in denial."
*Allo as in "both allosexual and alloromantic."
And you know what? That can be true. It was true for me. When I was younger, I identified as bisexual heteroromantic (WLM). My understanding of attraction was "sexual orientation = your real attraction, romantic orientation = who you choose to date."
I knew that I was definitely attracted to girls, but I would only date guys, and I figured that dating guys must mean that I was attracted to them as well. I'm a lesbian. Or, I'm a polysexual person who is attracted to many genders, but not binary men, if we want to be more precise. Point is, I was experiencing compcishet* back then.
*I'm using the term "compcishet" instead of "comphet" because I am nonbinary/pangender, and my comphet was based on a cis lens. I was still presenting as a cis girl at the time. I felt obligated to conform to being cishet, not just het. So, it's compcishet, not comphet. Attraction to men wouldn't be fully "het" with my actual gender in mind; any attraction I experience is gonna be a bit gay.
It's also interesting to look back on how I thought romantic orientation was "just a choice people made," because... Now I know I'm just aromantic. Of course romantic crushes weren't a "real thing" to me... I didn't experience it. I didn't think anyone actually did.
So, my use of the split attraction model back then as an "allo" person was absolutely caused by compcishet, as well as a severe misunderstanding of how attraction works. You know what else was caused by those things?
Me identifying as bisexual. Me identifying as heteroromantic. But bisexual people exist, as do heteroromantic people. Yeah, those things were wrong for me. Those things were a result of compcishet for me. But that is just my story, and it does not dictate anyone else's. And, just as a person can be bisexual or heteroromantic, a person can also be both.
Is it good to introspect on why you identify that way? I believe so. Is it possible that you're using those labels as a way to avoid addressing your true feelings? Of course; I'm evidence of that possibility. But if you conclude that you are bisexual and heteroromantic, or some identity in a similar vein to that, that is completely valid, even if you end up changing your mind.
Anyway, this is not an invitation for discourse, I just wanted to rant.
