I'm not sure just where this idea of cabeceo = women/followers have to be passive comes from,
It comes from an older culture, perhaps/probably an inherited, romanticised(?), perception, or maybe literature (e.g. Jane Austen?) of that culture where females waited to be asked by a male. Like it was the male who had to invite the female, pay for the night out, meal, etc. Of course, that got overturned from the 1960s/70s and, maybe coincidentally, around the time of the Pill and, so-called, sexual liberation. Also a post-WW2 time where women, increasingly worked - and had experience from war years, women's lib, with an impact on society.
Of course females in earlier eras worked the system to obtain what they desired.
If you like, it's a stereotype of previous eras. Males have had millennia of 'inviting'; females, about a century.
Nowadays, of course, we've moved away from the dance hall to find your dream partner! Any male who pursues some female, or is perceived to do so, may be held up as a molester. That may, or may not, be true. But we now have uncertainty about what's acceptable.
I suspect that makes us expect females to 'play the game', but the playbook has changed - at least for solos. Also the environment (lighting, seating, space, cortinas, general order, etc) isn't always helpful. So why play? It's now seen as mainly about the dance, not the person. Perhaps also too many 'traditionalists' who might be expected to object. You could 'lose face' on social media.
Cabeceo works when both parties use it as intended
Yes. But many 'milongas' aren't in a dedicated room as in BsAs (although maybe that's just a perception). That's not the home culture. In fact the 'dance hall' itself may be strange! They're not attended by young singles only, perhaps with chaperone, in a barrio where everyone is known, as are the couples (possibly parents, or friends of parents).
Nevertheless, given the appropriate favourable conditions, cabeceo/mirada can work - but it's often necessary to assist that in some way (e.g. walking over to be close enough to be seen, sitting and talking between tandas). Or maybe just workaround with some pre-arranged mental list, or social set.
You do the same when ordering at a bar/restaurant and trying to get the waiter/bartender's attention
But you also walk to the bar and ask! Or even order on your phone. You also expect some service!