Ok, serious answer. Reproduction taken out of the picture, the main issue with incest is relationship dynamics, and the idea that your blood family is a group of people who were fundamental pillars of the development of your personality and identity as you grew up (or you are to them), which means that a sexual or romantic development falling out could shake those pillars at best, or there could be an almost inherently abusive power imbalance at worst. You could find situations where a technically incestuous relationship wouldn't be a terrible idea (for instance, step siblings related due to half of their parents getting divorced and marrying someone else, who have only met each other after their adult persona already has solid foundations), but it generally almost always is terrible.

I mean it probably depends on what age you became step siblings, it has a very different vibe if you grew up together vs your parents remarried when both are in your late teens

Either way, I would find it pretty weird. But I guess there's nothing inherently wrong with it

I mean... I always assumed they were step just for legal purposes only, as in some countries it isn't legal that kind of porn. But honestly never looked into it so maybe is not illegal anywhere.

I can't answer that, but I've thought about the topic and I think I can answer why there has been a rise in step-porn.

I think it's pretty simple: people are more isolated, and people now socialize online.

We're simply seeing less of each other than we ever have (especially during the pandemic, but this isn't specific just to that timeline). Whereas we used to go out and socialize and develop crushes in the real world, for a lot of people, especially a lot of young men, these days the vast majority, if not all, of the non-online social interactions they're having with the opposite sex are within their own homes. And while our brains may be adapting to this new internet landscape well enough, I think our bodies are still lagging behind. When you're an 18 year with raging hormones, the sexual drive extends beyond the reasonable brain. And so it attaches to what your libido recognizes as the other sexually viable candidates regularly in your sphere of influence: the women inside your own home. And thus they develop crushes on their mothers, their siblings, their stepsiblings, and are turned on by pornography that lets them indulge in this taboo but still very real crush.

And to be clear, I am attempting to explain the phenomenon, I am not attempting to excuse or justify it. Incest is gross and faux/step-incest may be biologically better but is still pretty socially/culturally fucked.

I'm just glad I grew up in the 90s before our lives had moved so heavily online.

It's Charles and Gina discussing the upcoming Boyle family vacation. The original line is "'Tent' singular? Charles, 'tent' singular??"