Writing is hard work...
...if you've ever written for publication like I have. Oh, I am suprised, since you like Leonard Cohen, that you are so judgemental about a lady writer who fooled around. It takes two to tango, as you know.
Miller's wife, June, ran around on him and also had a triangle love affair with him and Ms. Nin. These things happen... Anais Nin happened to be talented and also did not reveal some of her affairs until her husband died to spare him the gooey details.
Miller, too, as you may or may not know, was also a talented writer who did watercolor paintings on the side to earn money. He worked very hard for Western Union for a number of years. He also lived overseas in France before World War Two. His writings were censored in this country for a while. I consider Anais Nin to be like an "Ann Frank" who survived World War Two and lived to see her work acclaimed.
Both Miller and Nin were also philosophers in their own right. They didn't have formal degrees in it or anything but they had a sophisticated world view. I don't consider any of their serious work "idle speculations". It's just ridiculous for you to think that.