I don't think it's fair to say suburbanization lead to isolation. I think factors like social media have had a much bigger impact.
It's not like you're living away from any people - you have 100 other neighbours living on your street!
100+ years ago, certainly more people lived in rural areas. In Canada and the US, pre 1900s, it was something like 70% of the population was rural.
Cars came in parallel with a lot of change.
Proximity doesn’t automatically result in interaction, though. If every one of those 100 people get in their private mobile room every time they leave their private mobile room there is no chance for any of them to interact.