I've attended the weddings of multiple friends from my first job. I'm still in touch with 4-5 people from my second job. I haven't spoken to anyone from my team at Google since the day I left. I had good, cordial relationships with all of them, but it was also incredibly impersonal. I don't even recall learning anything about anyone's spouse, for instance.
I remember when I got my first job I was extremely social and would try to make friends with anyone. But now that I'm on my nth job I don't feel the need to socialize as much and would prefer to put in my work hours and move on with my life.
I don't think it's a good thing though. Middle aged men especially, I think, generally could do with a wider circle of acquaintances.
I try to keep in touch with a lot of my ex coworkers every 6 months.
Some of them are actually very keen to catch up, years after the job.
I'm friends with people who I was not very friendly with on the job 18 months after I've left the place, after sending them a text message saying "how's it going."