Did we stop letting kids leave the front yard, or did they simply stop doing that themselves?
I grew up in the late 80s / early to mid 90s. We were allowed the roam around until dark. But that was also a more natural thing to do, as there weren't a whole lot of things to do inside (we had to ask very nicely if we could stay inside to play).
But as I got into my teens, indoor activities became more accessible. Everyone had a computer, the internet became a thing, you suddenly had more options than to just bike around or play. As I got into my young adult years, I noticed that team sports and things like that had dropped off significantly where I came from. Even in my small rural town we'd have 3-4 soccer teams in my age group...10 years later, they could barely string together a single team of teens to play for our town team. Many kids had simply lost interest, and were occupied with other things.
My context is that I was born in the late 90s: The main thing that lead to me prioritizing using the computer and playing with people online over in person was one of convenience. My parents did a really good job at making it a massive pain in the ass as a young teen to have a friend visit, or vice versa.
"Hey can I go visit X?"/"Can X come play?" "what time? did you already call to ask if it was ok? What did their parents say? Who's going to drive you, their parents or me? how long? Our house is too messy for visitors."
Very quickly I got sick of having to play 20 questions. It was far easier to just add my friends on skype, spin up hamachi, and host minecraft servers for us to play together online. No exhausting negotiation sessions with my parents, no worry that the scheduling won't work out, I just get to play.
Definitely not a universal experience, in that regard. But I think its definitely a component of it. Why bother trying to fight for the permission to be independent out in the world, when you could be digitally independent far more easily?
In the 90s/2000s, my parents refused to even let me go into the front yard alone because I'd get "kidnapped". 24 hour news made lots of parents absolutely deranged and plenty of people really thought kidnappers flew around like hawks, waiting for under 18s to be outside of the sight of parents for one second so they could swoop down and carry them away.
I tried to go outside a few times. Learned the hard way that it wasn't allowed. Plus many other kids weren't allowed outside either.
I'm old enough to remember Atari when it was new. Playing a video game at home was quite something, no quarters required! But it also had somewhat limited replayability. Doesn't matter how good you are, eventually Defender is going to beat you.
The NES was a radical departure in how games were played and how good they were. You'd never spend all day in front of the Atari, but you could with the NES.
Add to that the steady increase in the availability and affordability of cable tv, then VCRs and video rentals, and now the TV is even more central to the ordinary person's life. Then came computers, the Internet, etc.
I think there is definitely something to kids just not being as interested in going outside. Why would they be? All their friends are in the magic box in their pocket. Outside is where you get sunburn and ticks that make you allergic to meat.
Similar experience here. Lots of time spent outside until around 14, when I got my first self-built computer. After that more time was spent inside chatting with friends and playing games. It was self-isolation.
Of course around the same time my older brother, and all our friends were doing the same. So it was just natural to spend less time outside or hanging out with friends in person
I blame apps and products like WhatsApp and Nextdoor. We've created these online means of connection (and conflict) which allows us to communicate without having to actually meet anyone in person.
Absent these forced meetings, parents barely know their neighbors and consequently, their kids barely know anyone even two doors down.