The reason this is being studied and discussed is, the sheer volume of stars is so vast and has grown so much, that the ability to ascertain exact characteristics hasn't been reached yet. You're speaking as if you know, and if you did, you'd be the only one.
Well I do know that most stars are unstable red dwarfs. Also that most are binary or multiple star systems. I also know that most exoplanets are not located in a habitable zone. That’s common knowledge. What I do not know, nor does anyone, is the number of other conditions which might render a planet uninhabitable. They could be great or small. But as I said, the sheer number of exoplanets is not evidence of anything, nor does the lack of evidence constitute evidence in itself.