Data Processing was done with large machines the size of cars or at least major appliances. In order to make use of it, a customer would bring a problem to a person called a Systems Analyst, who would help the customer understand how Data Processing might help. Then the customer and the Systems Analyst would come up with a plan on how to get the customer's work done.
The Systems Analyst would bring the customer's problem into the Data Processing place, and give it to computer programmers. Along with other helpful people called Punch Card Clerks and Computer Operators, the programmers would produce software that helped the customer.
After that, when the customer had more data to be processed, it could be dropped off at the Data Processing place, where the Punch Card Clerks would put data in the software, and the Computer Operators would make sure the machines worked, and then finally the data would be all processed and given back to the customer in a neatly rubber-banded set of printouts on fanfold paper.
In the 1990s it was discovered that everything had changed. A customer could often mash fingers on keys and make the data process right there at the desk, without visiting the Data Processing people. Computers were interactive and talked right back to people, so that dropping off data and picking up printouts wasn't necessary. And worst of all, customers could talk directly to programmers, it was discovered, and tell them what they wanted, and these new quick interactive computers could give results very fast. The programs were then given to the customers who took them off and used them in their own offices.
So the Punch Card Clerks and the Computer Operators and the nice person at the desk who took the data and gave back the printouts were no longer useful, and they had to go home and stop working at the Data Processing place.
Worst of all, the Systems Analysts lost their jobs too. They were expensive people, since almost all of them were old programmers with experience who had been promoted. They were all fifty years old and not retrainable and didn't know much about PC computers or other new things. Their entire function had been removed, and suddenly their $60K jobs vanished. So all the System Administrators went home from the empty Data Processing places and sat in their imitation redwood veneered dens in their suburban homes and stared at the wall and drank highballs and then shot themselves in the head with large-caliber handguns.
It turns out that the computer programmers shouldn't talk to customers after all. They are very optimistic people, for whom everything is almost done all the time. They often refuse to finish things or write down how they work. And they can be mean and weird and not very easy to understand, so that customers become frightened and angry and don't want to talk to the optimistic people who don't finish things and snort a lot and wear fedoras indoors. Things like this happened during the 1990s a lot, and many customers didn't want to have any software if they had to talk to the computer programmers. It was time to bring back Systems Analysts. But they were all dead, because they had shot themselves in the head with large caliber handguns in their imitation redwood veneer dens.
So we have Project Managers now. They are different from Systems Analysts in that they are 30 years old instead of 50, they do not live in imitation redwood paneled dens, and they never did know how to program computers. They drive VW Passats and smoke marijuana and use lots of buzzwords, and they are very good at making customers feel comfortable. Many of them enjoy jam band music and are engaged to people named Chad or Alyssa. They do a lot of the same things the Systems Analysts did, so that the customers get their software but don't have to talk to the programmers after all, because that was a bad idea. They tell the programmers when things have to be done, figure out on their own how long things will take, and dress much better than the programmers.
And that's the story of how Project Managers were made.