Back when I started photographing one of the main rules or critiques I kept hearing and seeing on the photography forums or the places where people would give feedback to your work was for the images to be sharp and clear.
But as it happens with any advice, it’s very much contextual and dependent on the photograph (and here you can replace it with painting, drawing, writing etc.). Sometimes what you need or want to express follows no rules or needs new ones. That is why you might hear you need to learn the rules so you can break them. But successfully breaking the rules usually comes with intention and with the knowledge of why you’re doing it.
When it comes to out of focus images, I enjoy them quite a lot. They can convey certain moods and feelings that are far more expressive than a clear image. They tell more by hiding things. And sometimes I feel a bit out of focus too, so I put it in my photographs.