Google's John Mueller said on Twitter that they "never index all known URLs" and calls that "pretty normal."
This comes after a complaint that the URLs the webmaster submitted to Google via Google Sitemaps were not all indexed by Google according to that report. That is even true for a site as amazing as this one ;-P.
Here is John's tweet:
So no need to worry if ALL your pages aren't indexed by Google. Focus on your important pages and if some of those pages are not indexed, work on getting more links and views on those pages.We never index all known URLs, that's pretty normal. I'd focus on making the site awesome and inspiring, then things usually work out better.â" John â.o(â§â-½â¦)o.â (@JohnMu) January 3, 2018
Forum discussion at Twitter.