I don't see why it would have to correlate with age. When I was younger I used to get annoyed at late people more easily. As the years have passed I've developed my philosophy. I still think it's often a sign of selfishness but we all have our flaws.
Early on in any relationship I learn which style of timekeeping a person has. You get the people who will warn in advance and apologise profusely if they are going to be 2 minutes late, then at the other end of the scale you have the people who say "I'm just around the corner I'll be there in 5 minutes" and you know they might turn up some time that day/night, if they're having a particularly switched-on day.
Once I have my expectations set correctly I don't get annoyed. It does mean that any arrangement with the 'very late' style of friends always has a status of 'tentative'. And I make it clear to them that I may be doing something else by the time they arrive and that they'd better be able to handle that as it's a cost of their style of being. I've never known a late person to have any problem with that arrangement, they generally seem to quite like it as then they know they can do their thing and not worry about putting me out.
I've not read the linked article but I've been pretty constant with my level of making new friends throughout my adult life (am in my forties now). I've moved around a bit and lived in a few different towns/cities, had a few career paths, maybe that's relevant. I think some people narrow their worldview as they get older and perhaps this makes them more choosy about who is 'worth it'. I've always been a weirdo/outlier. I'm fine with loads of people around me and making parties etc., but also more than happy in my own company. I noticed quite early in life that I could be accepted in most social groups and drift between them and developed a distaste for cliques and the negative behaviour they encourage (exclusivity, "our love for each other is based on our hatred of everyone else" etc).
Early on in any relationship I learn which style of timekeeping a person has. You get the people who will warn in advance and apologise profusely if they are going to be 2 minutes late, then at the other end of the scale you have the people who say "I'm just around the corner I'll be there in 5 minutes" and you know they might turn up some time that day/night, if they're having a particularly switched-on day.
Once I have my expectations set correctly I don't get annoyed. It does mean that any arrangement with the 'very late' style of friends always has a status of 'tentative'. And I make it clear to them that I may be doing something else by the time they arrive and that they'd better be able to handle that as it's a cost of their style of being. I've never known a late person to have any problem with that arrangement, they generally seem to quite like it as then they know they can do their thing and not worry about putting me out.
I've not read the linked article but I've been pretty constant with my level of making new friends throughout my adult life (am in my forties now). I've moved around a bit and lived in a few different towns/cities, had a few career paths, maybe that's relevant. I think some people narrow their worldview as they get older and perhaps this makes them more choosy about who is 'worth it'. I've always been a weirdo/outlier. I'm fine with loads of people around me and making parties etc., but also more than happy in my own company. I noticed quite early in life that I could be accepted in most social groups and drift between them and developed a distaste for cliques and the negative behaviour they encourage (exclusivity, "our love for each other is based on our hatred of everyone else" etc).