The recommendation that people talk more to strangers should be accompanied by a warning that it can be a significant annoyance to no longer be surrounded by complete strangers when in public, and instead have people you've voluntarily conversed with previously, and may expect you to not ignore them in the future.

I generally like to keep to myself and focus on my own interests. In the past I've dabbled with being more social with strangers at cafes I would frequent. The end result was I stopped going to those cafes because it became a nuisance, since I felt obligated to speak with the people I'd spoken with before, but really had zero interest in speaking with regularly. They would start sitting by me while I was at my laptop working, and wanting to make small talk whenever they saw me.

Nope.