Creating backlinks on good web platform makes your content trustworthy to the search engine, mainly we create backlinks to make contents to be indexed on search engine as Google ,but only "Dofollow" attributed web authorities allow to get indexed by google.
"NO follow" is non other an attribute, that refers to Web crawler not to follow any particular link or hyperlink objects on web pages.
most of the link are considered to be skip by the web crawler but sometimes ,i have seen some "NO follow" link that has been indexed.
This initiative is to inhibit spamdexing .That means a webpage with "NO follow" attributes, it does not pass on link juice.
So its not 100% accurate that "NO follow" attributed link are never get indexed and it depends on the web authority and the content relevancy and value.
hope you get it helpful.