Generally, in my own career, most parents got good at working from home and got their jobs done.
Also, more childless people now get involved with eldercare, given an aging population with fewer kids.
There is a problem in logic if an employer has to reassign work to someone else other than the person paid to do it. The other person might not be paid at all (in a salaried environment) or the employer might have to spend more. A childless person could "lowball" those with families and be more likely to survive a downsizing or layoff later.