Can't totally agree that people switch jobs today unlike they did years ago. My brothers sons are on the same job for years now. One of them was going to quit for a better paying job and my brother told him "definitely don't do that. You have great benefits, descent pay and a great retirement package there. Don't blow it by leaving."
There are people that have City, County, State and Federal jobs that have been on them for years.
I did move around quite a bit and go from one job to another. The longest I was ever on one job was 4 1/2 years! That's not good when I was employable for 38 years! But, different things happened where I had to quit some jobs, got laid-off and even fired.
It's true that staying on a job for 5, or as much as 10 years today, was like staying on one for 20 years in the past.