I agree. In my opinion, it's another manifestation of individualism promoted by the capitalist system in the US - in urban design, in this case. Another commenter pointed out how they only see their neighbour when they both walk to or from their car at the same time. It sounds sad to me, but some might prefer it that way.

It’s mostly just fashion, no need to read into it so much with your own personal biases. Although it can serve a purpose if your house is on a busy road. It’s quieter the further you are from traffic.

Setbacks are often required but there’s quite a bit you can do even with that. Front yard barbecues are great!

There's a rented row cottage near my office where the front fence is made from timber pallets, and appears like a bar with built-in succulent plantings. The tenants at the time used to drag out stools and sit there and chat like it was a wine bar.

We've put seats out on our front porch with a view to one day remembering to actually sit on them. So far, it's just the neighbourhood cats snoozing there when the sun hits the right spot.

New Orleans has stups and porches. People use them. You have to meet your neighbors somehow.

Retired city planners never envisioned a world where we were so collectively anxious/antisocial that waving and inviting someone onto your porch 20-40 feet from the sidewalk would be considered a “sad” state of affairs. Is it the planning that’s in a sad state?

This isn't really the case outside of far-flung suburbs and rural areas. Where I live, setbacks of more than 6 feet or so are rare, and front porches and stoops right off the heavily used sidewalks are the norm. We do "porch hangs" with our in-building neighbors, our kids and the kids in the neighboring buildings do sidewalk chalk together, we hang out at the local parks together, bring over friends from nearby neighborhoods, and talk with other parents and stuff.

Being a parent in a child-friendly neighborhood helps a ton with finding a community. Before we had a kid, we'd do things like welcome new neighbors with treats from our favorite bakery and our phone number if they needed anything, being generous with our time and things, etc.