If a company likes (or doesn't care) that you have a child in your photo (as in this instance), that is one step closer to a culture match. If they dislike it (legally or not), why even bother interviewing? Lots of companies out there -- and from there perspective, lots of employees.
In other words, assuming that what you share is important to you (your children, family status, opinions, blue hair color), and they like or see no conflict with it, steps are being made to form a long-lasting mutually-beneficial relationship.
Why go through the stress of pretending you're some clone of the way 'professional' imagery was touted in the 1950s-1980s (suit, shaved face, short hair, child-less, family-less, career accomplishments only) when you are clearly going to have to get to know your colleagues, spend 40+ hours a week with them (or on Zoom, sigh...), only to discover later that you are really the odd one out.
If we want to give lip service to 'diversity', it will only get us so far. Granted, every company is different, and every person is different. Putting a pic of one's children on LinkedIn may not be for everyone, but it's a solid move in my opinion.
In many of my workplaces, I've had to deal with dogs, hear about endless dog stories, see pictures of dogs on desks, and be 'forced' to pretend that dog memes are 'so cute' on Slack. Overtime, I've learned to just accept it. At first, it seemed weird and out of place at work (to me), but after ten years of it, I've become more tolerant about it. To dog people (you know who you are), their dogs are incredibly important to them. I may not ever want to own a small yapping dog, but I can appreciate more now that to those that do, it's a big part of their life. Near as I can tell, it enhances their life and doesn't detract from the quality and commitment of their work anymore than children do for dads and moms, or ultimate frisbee does for college students.
Let it go.
He didn't put a picture of himself wearing a Star Wars Resistance Pilot helmet on his head. Let's keep it in perspective. (Although if he had, I'd hire him on the spot).
Such photos are not public by default, and should stay private to you and the circle of your friends and relatives.
I think the point of this post was that they're trying to show that somebody who publicly demonstrates a commitment to their family, vs full time dedication to career, will be offered fewer senior roles.
But I see it from a different perspective. How would you feel as a 14 or 16 year old teenager someday in the future knowing that your parents had posted hundreds, or possibly thousands of photos of you from birth up to early teenage years all over the internet with no privacy precautions whatsoever?
I think at least some of us are fortunate enough to have grown up in the time period before widespread full-saturation use of camera phones, and parents who take pictures of literally everything and share it publicly as widely as possible.