Earlier quoted context omitted.
I've found that it's more about the person than the area. My friend is an urban activist and he always complained that his childhood neighbourhood wasn't conducive to meeting people. Recently I learned that we actually grew up just a few bus stops from each other. For me it was never an issue to hop into a bus/subway train and reach my friends - usually unannounced.
Easy to meet people, and easy to hop on public transport to visit existing friends, are two very distinct things. How did you meet these people who were not within walking distance?
The only people my age in this new neighbourhood were bullies and/or juvenile delinquents, so I didn't make any friends there.
My closest circle currently is my class nerd group from middle school with one additional guy from a high school the two of those went together. The urban activist friend I met through another guy from this bunch, who introduced me into some extracurricular activities in his school which I could attend.
I also have college friends who, like me, didn't move cities to go there. One of them is actually a guy who my primary school friends met in their middle school and who went to my high school, but we only got to know each other better in college. We were all spread out over this 1.7mln city, but that was no problem since everyone had phones.