yes and also the fact that they are very different from each other, you can't mix their faces or overall body and personalities. They all had charisma and were cool while performing since debut.
Tbh when I first got in kpop and I was new, I mixed and couldn't differentiate even my first bias group Members and many others, but never with blackpink. They definitely have distinctive looks. Also no offence, but even now for example with illit or new jeans, they look so similar to me and I cant say whose who, even tho I know their names (again no offence)
Tbh I think this comes with time. I have noticed that at their debut, groups often don't give their members very distinctive images, like a signature hairstyle and stuff like that. Over time, each of them develops their own style. Like, looking at BP debut photos and MVs, they look way more distinctive now than back then.
We can already see NJ trying to do something similar with giving in particular Hanni and Danielle signature hairstyles (Danielle with curly hair, she does have natural curls btw, and Hanni with her Bangs and shorter hairstyles like in OMG and this comeback) and marketing Haerin as the cat member (which works very well, her silent personality traits are often associated with cats. The company made a very good choice with this type of branding). We'll see what they do with Hyein and Minji. I suspect that they will turn Hyein into the model member, since she is the tallest and also has the most model-like facial features. And Minji will definitely be the actress of the group.
We can also see Blackpink doing something similar, with Jennie being the "Model" member, Jisoo being the "Actress" member, Lisa being the "Brand" member and Rosé being the "singer". For NJ, it's probably gonna be Hyein being the "Model" member, Minji being the "Actress" member, Hanni being the "brand" member and Danielle being the "singer". I wonder if they will market Haerin as a dancer.
Sorry for writing that much LOL. About the actress thing, ik that Jennie obviously acted too, but I mean like the typical korean actress idol like Suzy