Let's not forget, a man's career would be advanced by having a wife and kids to support. If a boss was deciding between two applicants, the married guy would get it. Families were there to help a young couple out. In my family, they'd have a house-raising, a barn raising (usually in the opposite order), and every new couple got a goat.
Now, not only does a man pay no price for sex, he pays no price economically. In the old days, a guy who could provide for a family, who choose not to be married was weird or even considered sinful by some. Society, in general, has taken ALL the pressures off young men to grow up.
I take that back. Society has actually made it a negative for a man to settle down. Young men are bombarded with horror stories about divorce and married men are universally portrayed as dumb fat jerks who's wives have to carefully direct and manage. The message is clear. If you are dumb enough to get married you will pay a heavy price.
It even hurts them at work in some cases - the "married guy" being seen as less willing to work the 70-hour-weeks often expected of twentyish professionals trying to work their way up. Plus the company is on the hook for higher health-care expenses for two people plus future children.
As you point out, being married used to be an asset to a job-seeker - no longer.
The usual presumption was that he was a homosexual.
Society, in general, has taken ALL the pressures off young men to grow up. I take that back. Society has actually made it a negative for a man to settle down.
Preach it! I'd add that there are many women out there who don't grow up, too. They're permanent stuck in adolescence because their parents spoiled them rotten rather than put up with their 13-yo temper tantrums. The Peter Pan syndrome applies to both sexes.