Even if that's true, it doesn't tell the entire story.

For example, in 1960, the USA was at the end of a 15-year period of building new jets, missiles and rockets. Every guy coming out of college with an engineering degree (and the GI BIll meant there were a lot) had a place in a growing industry. Everybody who wanted to got a lot of hands-on experience. The defence industry was taking shape, it was not a mature (some say 'ossified') industry and market.

There were many companies involved. We hear some of the names today, Boeing, Lockheed, Northrup. But the aerospace/defence industry in 1960 had probably 3 or 4 times as many companies in it. There were a ton of what we would call "senior engineers" today who had a number of projects behind them.

There might have been a distribution where the average engineer was 28, but that means little in comparison to today. We have far fewer companies, which means far fewer senior engineers, and those engineers don't have the range of experience, or the hands-on experience that a senior engineer had in 1960.