Just playing the role of devil's advocate here, but perhaps the manufacturer knows that women and gay men make up to demand for lifestyle magazines almost entirely (including Men's Health/Fitness which is just a bunch of photos of super fit dudes). They're pandering to their audience, which is probably why you dont see many dads.

Not saying it isnt another tactic to shatter the illusion of a nuclear family, but they're probably just saving their asses from the woke SJWs who would throw a hissy fit if all the parenting covers were of a husband-wife family.