half the people arguing aren't reading the situation properly, or don't realise what kind of events people are talking about.
It's the same sort of thing as with a hobby group I'm in, where people go to the pub afterwards. It's open anyone to come. Some do regularly, some occasionally, some never - for all sorts of reasons. Sometimes the conversation at the pub turns to a film/play/event and people decide that it might be fun to go as a group, and whoever is there says they want to join or not. Sometimes people who are there happen to remember a few others that they know well and asks them if they want to come too, but not always. The event happens, and some people who might have liked to come perhaps didn't know about it. But it's not a big deal; they could have come to the pub if they wanted, and become part of that group who tends to organise things together, or not. It's nothing official, it's not organised 'for' the group in any way, but at the same time, it's more inclusive than some things because it's not just a couple of people arranging it with their own friends - it's being open to anyone who happened to be there that night and wanted to come, even if they weren't normally part of stuff like that. They just had to make the choice to go to the pub in the first place. There are valid reasons why people don't want to or can't come out afterwards some weeks, and that's fine. But it's not deliberately excluding them because someone doesn't then find ways to extend the information that we're going to a film on Friday to all 80 members of the group. It just happens that those who were there became part of the plans.
And FB interactions can be very much like that. They're open if people choose to join in, and you can include people you wouldn't really know or invite otherwise, because they happen to be there.
And if people choose not to join in, totally up to them - but the point the OP was making is that some people get very snippy about the fact that they don't hear about stuff, whilst at the same time, being incredibly condescending about it. They're the people that are being complained about. The ones who say "how can you stand FB with all the trivial stuff and posts of people's dinners and bragging and so on; I'd prefer to enjoy my life by talking to people for real" - and then find that there might be a snippet of news from an old friend that people are talking about, etc, and get cross that other people know this/talk about it. It's their attitude that is the problem - as if the rest of us actually enjoy looking at photos of other people's dinner, because they assume that that is what is on FB since it's a sort of media stereotype (when actually, if you choose your friends well, and learn to block what you don't want, you only have to see the sorts of things you want to see, from the people you want to see them from! It's a lazy criticism from someone who doesn't know how to do that, or doesn't have friends who post anything interesting).
They're the ones who are being complained about - the ones who genuinely feel superior to others for not being on FB, yet at the same time, moan about not hearing about stuff.
Can't be online/can't afford it etc and feeling excluded - yes, fair enough, and maybe this can be helped
Choose not to be on, and don't care - fine
Choose not to be on, feel you might be missing, but realise that's what happens and it's nothing deliberate - fine
Choose not to be on, tell people who are that they're superficial and shallow because they are, and then moan when you don't hear about something - not so fine, and that's the group that the OP is talking about