Another thought with the planning thing--some people are just good at planning. They not only have the confidence to issue invitations, they also think through the logistics--where to eat that will accommodate everyone's diet, how Bob without a car is going to get there, what hours won't conflict with Alice's gym schedule, etc.. That's above and beyond the etiquette requirement, but it helps ensure that everyone will actually be there, because they don't have to do much work for it. Of course, all that is more work for the planner, and I can see how they would get tired of doing it.
But, sometimes that means planners have very high standards, and if someone else tries to step up and plan something, but isn't quite as good, the planner can get huffy about it, and that can be intimidating to people who might also lack some self-confidence as well. The planner can be seen as saying, "I don't want to plan, I want someone else to plan, but they have to plan it just like I would have." I'm not saying anyone here has done that, of course, but I've seen it happen in groups.
Regarding friends--I don't have that many friends. I almost exclusively meet them through work, and I've found that a lot of people are not good at maintaining long-distance friendships once they move away. I maybe have a couple friends still in town that I see a couple times a month. The others are all over the country/world, and sometimes we exchange emails, but it can be very sporadic.
The weird thing is, I'm actually better at keeping up with emails than I am at doing stuff in person, so when someone first moves away I try to be really good at keeping in touch with them, only to have them fade away eventually. On the other hand, I'm not interested in going away to visit people in their new home and it's hard for me to meet them somewhere without a lot of advance planning, so I'm sure I've disappointed people in that regard.
This thread is fortuitous, because I've been thinking about the concept of friendship lately, almost wondering if it really even exists. I feel like even my closest friend doesn't really know me that well, although frankly I'm peeved at her right now for being so distant to me after my recent surgery, so maybe once I get over that I will feel closer to her. I like to put numbers on things--I feel like there's nobody who knows me even 70%, and the highest would actually be my mom in the high 60s, with my closest friend more like 50-55%. Do other people feel like their friends know them better than that, or is that about typical?