Confusion

they're okay with rape but they're not okay w two adults not related by blood knowing the full consequences of their actions choosing to be w each other

Because usually the violence especially examples that you used tie into the plot/story like if im reading a horror or thriller comic id expect that?? Incest is usually unnecessary and put in there for fetish get off or the shock factor and universally gross so most people wouldn't stick around if the incestuous relationship has no impact to the plot. I mean.. its not really confusing and people don't have to like it no matter what else they like lol.

Im honestly ok with anything as long as the story's good idk why some people make such a big deal out of small stuff and turn offs and ruin a good story for themselves

I mean, personally, I don't like any sort of gore(?) in romance.
If they just grew up together, as if they were siblings, but end up in a relationship, I don't see much of a problem. Although, if their parents are married, and they're step-siblings, I feel a bit uncomfortable reading it.

Obviously just my opinion, no hate towards anybody.

People need to differentiate reality from fiction, or vice versa. The reason why I read manga/webtoon is to get away from reality so I enjoy reading wacky plots where there are no rules.

I think it's because when the author portrays crimes they show crimes are bad/don't do them. And we acknowledge that crimes are bad and for whatever plot they are part of they serve their purpose.
But incest or pseudo incest in these stories is romanticized. Like being raised as siblings or calling them your sibling and one day flipping a switch and having romantic feelings makes me uncomfortable.
And also if you can't relate to plot points at all it's much much easier to separate fiction. But being a person with siblings I could never imagine feeling that way towards them (And the fact that characters contemplate it or pursue it is just weird to me)
Also to clarify if I don't like a trope that is central to a plot I won't read it. And if people do enjoy these plots I don't really care

Agreed

I see your point however there are also stories where the main character is anti-hero or villain-like where they do crimes just because they can do them. They're not really portrayed as people who are kind. There are also people who prefer these types of stories and prefer to "be" the villain than the hero. Doesn't this also count as "romanticizing" being a bad person? I also have siblings and for me, no matter what I read or see I'll also never be able to see them in any other way. I guess it just differs who reads it and the way they can separate fiction and reality.

the incest op was talking about was like adopted siblings kind. like say for example, Crown of the Deep Green/The Viridescent Crown.

ok revision, not adopted but like stepsiblings sry. but i think op put the quotes around incestuous to say that its not rly incest. cuz no blood relation

Romanticizing in many situations isn't a good thing because it glosses over/makes something seem better than it is. I myself do enjoy anti-hero plots and I'm aware that what they're doing isn't the most heroic (as the name suggests) but it's an interesting twist to a normally conventional plot. My biggest issue is that I analyze pretty much everything I read so it's very hard for me to gloss over/forget plot points that make me uncomfortable.