> Does intimacy somehow lend knowledge of whether someone's looking for a long term relationship?

Intimacy also implies letting one's guard down and revealing your "truer" self to the other. So yes, it can give better insights about someone, and thus offer more reliable hints on the possibility of long-term relationship. In the Victorian era women "dated" in the public glare of a social setting (public or private get together) or with a chaperone in tow - so obviously it was hard to be physically or emotionally intimate with someone. Even if you could find opportunities to be intimate, they were rare and limited enough that one may still not get enough "data" on the other person. Compare that with modern times and culture where couples today can freely be intimate in many ways without any societal judgement.