After I wrote the original comment, I started thinking, even if you accept that hobbies / skills / preferences are a vector, what is the model where it makes sense to multiply vectors together? Then I thought, what if every time people encountered each other there was a kind of vector multiplication, about the salient aspects of their vectors? And this resultant "encounter vector" served to motivate the encounter, and potentially update each person's original "personality" vector? And day-to-day life could sometimes result in self-multiplication, depending on what you're doing.

That seemed fruitful, though obv very incomplete. I mention it in case you want to return volley :)