The funny point of Google+ is that the project has declined. Google has tried out to build his own social network, but it doesn't worked. A while ago i was active on Google+ and posted something into the groups. The idea was to give the project a chance. Google+ was never recognized as a real social network, mostly because noone was using it. The only active members in the network were spambots who are posting URLs all the day, and even without such artificial traffic the amount of postings in the groups was low.
What is interesting in the Google+ example is, that the design of the website looks very similar to the Reddit page. Similar to Google+ the users has not to be logged in to see the content. And in most boxes some fance images are displayed which generates a large amount of bandwith consumption. The difference is, that Reddit is according to Alexa a top website which is on rank #20 worldwide, while Google+ is no longer included in the top100 Alexa rank. Even if some of the Reddit groups look a bit empty, for example the subreddit group of the Forth community which contains of 1500 members but the amount of postings is around 15 per month. And a Reddit post is nothing more than a title plus a URL and in most cases the title is the same like in the referenced website outside the reddit network.
We can say about Reddit that at least the mainstream groups which are about cat pictures and movie announcement are frequently used and generating a lot of user engagement. So Reddit will not become a second Google+ which is closed without anybody has realized it.
But perhaps we should ask a bit more critical what exactly social networks are about. In the positive sense they are filtering information which are available outside the social network. That means, newspapers, bloggers and youtubers are generating content in the internet and the social network stays on top of the content and is referening to the content. Can this job done by the content plattform itself? Youtube for example has on the right side a navigation bar which displays videos similar to the shown video. If the user likes to see more of the same content he can click through the menu and doesn't need to visit a Google+ with the best videos in the world. So what exactly is the purpose of social networks?
Suppose the orginal websites like Youtube, Wordpress and bookstores doesn't provide some marketing information. If youtube would disable the recommended videos, and Amazon would no longer display similar books, then Social network will become an important place. It would be higher authority which is telling to the user which books they should read and which videos they should watch. Unfurtunatly, most platforms are not only show the content itself, but trying to guide the user to more content on the same website. That means, the user gets a stream of content without leaving Youtube, Amazon or a newspaper website and this makes it hard for social network to generate an extra value.
Suppose somebody has posted a URL to Google+ which directs the user to a wordpress Blog. Why should anybody post a comment in the Google+ group if he can comment the blogpost on the original website? This question is hard to answer. Google+ failed in doing so and this was the reason why they have shut down the social network project.
Let us explain what was not possible on Google+. It was not possible to upload a video, to upload longer texts, to ask a programming question. If the user has done so, the moderators of the group has deleted the post or the post was ignored by the community. The intention of Google+ was not to become a bloghoster, a fileserver or a videohoster, but the idea was to filter information located outside the social network. Most Google+ users have not understood the concept. They were forced to become a member of Google+ but never have done anything within the network. In contrast, the users have very well understood what Youtube is. If somebody had created a nice video, he simply pressed the upload button and the video was online. Such a feature was interesting 5 years ago and it will be in the future. The worldwide users of youtube are using the upload button very often. What they haven't used is the post button in Google+. The reason is, because if they have uploaded their video already, there is no need to explain to the world, what they have done 5 minutes ago. The video is added automatically to their timeline and it is shown in the sidebar of the existing content. And people who have subscribed the user have seen it anyway. That means, youtube was working so great, that no extra social network was needed to aggregate all the content into groups.
Let us describe what the problem with Google+ was. A website contains of a sql-database which is storing the rawdata. And the question is how complicate is the process to produce this data. In case of Wikipedia it is very complicated. Because in the SQL-database the content of an encyclopedia is stored. Creating a single Wikipedia article tooks week. And if the content gets deleted it would take the same time to create the content again. In case of Google+ the amount of work to create the content is smaller. If a typical Google+ groups contains only the URL to external website, that the content is equal to a list of 1000 URLs plus the date. Creating such a list by hand or with a robot is an easy task. Even if the list was deleted, it's possible to create a similar url list within minutes. That means, in the Google+ sql database no important information was stored. And because no relevant data was in the database, the user's have no advantage to stay longer on the website. After a while they have recognized that all the images are the same, and all the URLs are referencing to content outside the network. What the users have done was to follow the links but not going back to the Google+ website. They clicked on a youtube link, liked the video very much and then they remaining on the youtube website because lots of other funny videos are there.
In a discussion it was asked why reddit is different from Google+. https://www.quora.com/How-do-Google+-Communities-compare-to-reddit The answer is, that Reddit has more users, allows nested discussions and Google+ is not searching for duplicate links.