Because relationships are complex and human beings' brains always instinctively look for patterns.

But also, and this is worth mentioning: Some things don't need an explanation, they will always and in any shape or form be bad. Red Flags of any kind belong to this group and the real question's less about whether they're bad and more about whether a particular red flag seems worth enduring to a person for the sake of love.

People's scepticism comes from experience in most cases. Abusers are great at making it seem like they and only they are different from all the other bad people, like they are just tragic heroes in a tail about life trying to screw them over. Once one compares the things all abusers say, however, it's obvious that these mindsets aren't so much about feelings and more about evoking sympathy in the abused people.

There's people out there who are dating i.e. pathologically jealous people successfully and it's totally okay for them to do so. But unless this person's really good at explaining why they are knowingly, voluntarily and unharmedly putting up with this kind of behavior in their partner, people will always worry and that's a good thing. There's more people out there who do not know, who do not actually endure this stuff voluntarily and who are indeed harmed in the process. And it's those people who, at the end of the day, need far more help.

So, while I understand that it can be frustrating, I don't want this thing to change ever bc quite a lot of people need that exact kind of advice. And for the rest, a simple "I have decided because it's my right" goes a long way. It's not like anyone was obligated to justify their decisions.