This is a fascinating thread and quite interesting to read the many views. I do not use facebook on a personal basis simply because I could not be bothered with yet another social media circus but I use it for business and although I do not advertise, it delivers its primary purpose: to connect with people. It is a powerful networking avenue but like most things in life, it has its positives and negatives depending on what you use it for.
We live in an expanding universe and if it stood still, we will all be bored out of our minds. Through this expansion, there have been so many inventions which serve us well, otherwise we would never have been able to be exchanging these wonderful view points on this forum!
Everything done and used in moderation is beneficial but when people sit in front of television all day long or chat nonesense on FB for 10 hours each day, then it is quite obvious that their brain cells will gradually begin to go to sleep. Television for example can be so useful to learn about wildlife, the natural world or commedies that make us laugh and persoanlly, outside of these and perhaps for about 3 hours a week, I do not switch the television on.
There are so many wonderful things around us and personally, I prefer to see the "half full" and if it doesn't serve me I move on. Having said these, as I do not have much experience of facebook except for business reasons, it would not be fair for me to comment beyond these. Whatever your choices, be lucky