Maybe people are just rediscovering hanging out in person. I know that I, personally, get no value out of Facebook, whereas I get a ton out of hanging out with people.

One other thing that may be contributing is that on Facebook, activity is required. Facebook has no equivalent of sitting back, relaxing, and silently watching a movie with people.

If I tried to get them to switch to another party planning service, I know the answer will be 'It's too hard to get everyone to make an account there. We've already got accounts here.'

Facebook is so ubiquitous now, it's like email. It will take one hell of a competitor to kill it.

Similarly, if something threatens Facebook's position, it's quite possible that it will be a substitute product, not a direct competitor. A significant substitute product of Facebook is real life interactions with your friends, for example.

I think that's totally missing the point. I don't think anyone uses Facebook as a substitute for real life interaction. I imagine that most people use it partially to coordinate the meeting up with said friends and partially to interact with people whom, due geography or various life circumstances, it is infeasible to meet up with in real life. I doubt there are many people who'd rather sit at home and read their friend's Facebook updates if they have the option to pop around the corner and meet them face to face.

Unfortunately they don't post as often as I would like - instead preferring to talk "face to face". :-(

Over time monopolistic players start to be everything for everybody. This may be just fine but in addition to that they promote bloat at the expense of their main product's usability. That's when new players emerge.

-- approximate quote from someone I can't recall

This is not quite exact in reality, but I think it captured the difference in essence between the two social platforms.

It used to be true that I only had friends on Facebook. But nowadays I have way more acquaintances than friends. My point is, if Facebook was still today only about people I am friends with I would still use it as much as 4 years ago. But nowadays the signal to noise ratio is way too low for me to really get anything out of the platform:

* I'm reminded of birthdays of people I don't even know how I met

* I see pictures on my news feed from people partying that I don't recognize...

PS: I might not be a good example of the average user, since I've also been moving from one country to another over the past few years accelerating the process by witch everyday friends turn into acquaintances

EDIT: fixed formatting