you can, but it's solely dependent on the context and topic of the conversation.
in a large gathering, for example a comic convention you can talk to people about their comics, as it's the entire point of these gatherings
out in the general street there's not much that's available to connect on. points of topics will usually revolve around asking questions on how-to's and weather, and depending on the mood of the person they can just tell you to fuck off, politely shy away from the conversation, or engage. However, very few of these engagements lead to meaningful friendships or relationships.
I was on the subway platform at 9 AM waiting for the train, see some guy sit next to me and I comment about how fucking cold it is. He replies yeah, and we talk for a bit about how the winter this year is supposed to be worse than last year according to meteorologists and climate change. Eventually the conversation falls into a lull, and we part our separate ways not before he hands me a card with his number
its scribbled on a worn out scrap of paper with a sharpie, and turning the paper over it's a list of addresses for HIV clinics in the area
the point is, I wasn't going to call that guy, its fucking weird. we shot the shit to pass the time, but things like this don't end up into great relationships out in the street.