I'm going to say right from the outset, that it did seem strange that Archie Comics would have an out asexual character before The Wicked + The Divine.
But it is something the creative team have been considering. In his Writers Notes for The Wicked + The Divine #13, Kieron Gillen writes, regarding Tara's sexuality.
I considered that perhaps Tara should be asexual early on. The juxtaposition between how the world sees her and what she actually desires was an interesting angle. I decided to not do it, as I think the story would imply that she's asexual because of her experiences, and by implication that asexuals are actually fearing sex and intimacy because of something that happened to them rather than an expression of their identity. As in, Tara is asexual as the world has fucked her up. Clearly, that's not something I would ever want to imply in a story. I suspect I could have written around that, but even explicit in-text explanations don't stop people taking an unwanted implication (e.g. Prodigy's Bisexuality in Young Avengers – David's explicit "No, I didn't catch Bisexuality" statement didn't stop people going that way) and when there's so much else we've got to worry about in this issue (and things which if they went wrong, would have been disastrous) I decided it would be overloading the issue. It was one which needed to do everything it chose to do as good as it was possible for us to do it. The more you add, the more impossible that becomes.
Plus introducing an asexual character and her dying in the same issue is also a problem.
Well, a few issues on, he appears to have approached the issue from another angle. In today's The Wicked + The Divine, we have a conversation.
With not one, but two of the gods, Urdr and Dionysys mentioning, in passing, their asexuality – one stated, one surmised. Though since she disappears for a lesbian S&M 3 way at the end of the page, you can probably count that out.
It's not a big thing. But it's a thing. And may have doubled the prominent asexual comics characters being published right now.
Basically, it's not just Jughead.