I see "free social interactions" as neither a benefit nor something that can only be obtained on-site.
These "free social interactions" are often just distractions - taking you out of your context, making it difficult for you to be productive.
That's why I love remote + Slack. Slack is async. I can finish what I'm doing before addressing messages there. On-site, people rarely if ever warn of their intention to come talk to you - they just walk up and start talking.
On Slack or Zoom you can't take a walk around the office to clear your head/take a brief breather and inadvertently bump into a person who asks a question about your t-shirt or new Apple watch, which then leads to a longer convo, which leads to grabbing coffee in the kitchen, which leads to you hanging out with that person and their group of friends over the a weekend.
Lack of social interactions makes most people miserable, lack of productivity is irritating but you can live with it. And although you can fix social interactions without an office it demands effort, so isn't free unless you live with people like spouse or kids. At work they pay you to talk with people, so social interactions there are free since trading effort for money is the purpose of work and the social is just a side effect.
These "free social interactions" are often just distractions - taking you out of your context, making it difficult for you to be productive.
That's why I love remote + Slack. Slack is async. I can finish what I'm doing before addressing messages there. On-site, people rarely if ever warn of their intention to come talk to you - they just walk up and start talking.