Google+ is AFIAK dead. I got a message to download all my stuff (the huge amount of one post) before it was deleted. Two others have accounts with zero posts, three more have almost empty accounts--if I were applying for a visa I can easily see them thinking I am being deceptive. I have no interest in simply sharing details of my life, 99+% of my stuff on the web is Stackoverflow and discussions such as this board.
I can see one on that list that could be problematic for some people: Reddit has a lot of support groups. The system is set up to support secondary handles for posting on such groups. People would not want to reveal such handles.
I can also see a problem with their approach. At times I have looked around the web to see if my name is unique--and if it isn't anyone else with it has no appreciable web presence. However, I have found a substantial amount of text attributed to me that I did not write. These all appear to be cases of someone scraping an existing board and using it to populate a board of their own. Whether this is about fake links to fool Google or about pretending traffic where it doesn't exist I do not know. The thing is the scrapes were poorly done--in multiple cases I figured out that the material in question was something I quoted but there was no longer any indication it was a quote, the words appear to be attributed to me.