I have been a Google+ user consistently since 2011, and over the past year in particular, activity has massively dropped off. I think Google+ is finally running out of steam, after many years of ghost town jokes.

Used to be there was a decent point in G+ for brands being integrated with Google Maps/My Business, etc. but Google's moved heavily towards removing G+ integration with most of their products, and that perk doesn't really hold true anymore.