Ok I'm just gonna straight up ask: do people actually like "oh no stepbrother" porn? What's with the huge proliferation of it? I only watch it because it seems like 80% of the well shot, quality porn is step family shit, and I'm wondering if I'm participating in some kind of bizarre feedback loop where step family porn happened to be a category that started getting higher quality production value, which got more views, which led to studios erroneously believing people were watching because they have a step family fetish. I just try to ignore that aspect.

When this has come up in the past the conventional wisdom seems to be the other way around. At some point they noticed that if they slapped a stepfamily label on an otherwise normal vid that most people wouldn't care and still watch it, but it'd also attract the fetish crowd. This way they get more views for the same content.

My assumption is that it's just easy to add and widen the audience to a random shoot? You put in a few lines of dialogue at the start and change the title, and it's not seen as so taboo that viewers will turn it off from that. But it gets some dedicated perverts searching for it where they might have ignored it before, etc.

They have some kind of story and buildup, the thrill of doing something morally objective, sometimes the "getting caught" aspect

... or so I have heard

I typically watch porn with the audio turned off, because all of the dialog is just so bad in one way or another. I'm not there for the dialogue, and I don't care about the fake set-up before the actual porn starts happening.