And I think it's fair to say that extroverts value that glue more than introverts, generally speaking. For an introvert, the value of the glue may even be exceeded by the cost of discussing some random nonsense they don't really care about.
I'm very introverted myself, but I realized if I'm trying to make friends or whatever I have to deal with the small talk.
I think there is a vanishingly small amount of people - even amongst introverts - that will jump straight into the deep end of a discussion with someone right off the bat. Most of my introvert friends also engage in warm up small talk before talking about whatever it is we talk about.
That said, I don't make small talk with strangers unless I'm interested in making them a friend or acquaintance: so I suppose your opportunity cost perspective still applies, as I definitely don't make small talk just to make a silence more comfortable.
"Hi neighbor, it's nice to see a familiar face. I'm glad to see that you are alive and well, as am I. I am still a normal non-creepy person who lives near you & who cares that you are doing well. If you ever find yourself in a jam eg. locked out, I'll try to help you, and hope I can rely on you to do the same for me. But I don't necessarily want to be your friend, and I realize that you have other things going on at the moment, so I won't bother or distract you with a conversation that takes longer than an elevator trip or requires emotional vulnerability or introspection."
I think we don't say these things in these words because it takes too long, and it requires engaging with someone on a more personal/honest/vulnerable level than they may really be comfortable with given that I'm basically a total stranger.
It is the purest form of empathy and yet unfortunately also the most invisible kind.
Hell, I know people who tend to help themselves into dumb conversations while the other person reads a book or does something similar. No empathy here.
This is, I believe, to cover discomfort coming from silence and such conversations, while not completely pointless, often have little value. They would talk about just anything, to combat this feeling. Weather is a good topic because most people can relate and it is rarely annoying.
I would say that both intro- and extroverts can act like this but conversations started by introverts tend to be more awkward. I think that lonely people are more likely to start valuable conversations.
Sure, for their mental model of other people they're being nice (and in some cases they actually are) - but not everybody has the same mind or preferences. True empathy is built on understanding that.