What does it mean to be a ‘heavy’ or ‘light’ follow? No, seriously, what does it mean?

I’m getting pretty curious about how these ideas and words circulate.

I haven’t heard a decent international teacher use the idea of ‘heavy’ or ‘light’ follows in years. But I still hear it at a local level.
This makes me think that either local teachers aren’t updating their learns regularly by taking classes/workshops (for whatever reasons – cost, time, inclination, etc), or those mid-level traveling teachers who do a _lot_ of teaching are still using the term and concept.

Anyways, now I’m starting to think about these quick-fix jargon type words (frame, light/heavy follows, compression, extension, etc), I’m wondering what people really mean when they use these terms.
It doesn’t seem to be used in reference to leads, which immediately makes me suspicious.

There seems to be this persistent myth that follows are 90% responsible for connection, which is then related to the idea that a good follow ‘just follows’, which suggests that following is magical unicorn trait. That tied to this inexplicable ‘heavy/light’ thing suggests some scary stuff about body size/weight and gender.

To turn it back into a teaching issue, how exactly does using this term and concept help people learn to dance?
What exactly are teachers trying to communicate to their students when they use this language?
I mean this as an honest question.

What is the difference between a ‘light’ follow and a ‘heavy’ follow?
The former responds really quickly to a lead, with no delay? The latter takes longer to respond? If this is the case, then how do we account for a follow takes the ‘right’ amount of time (eg 8 counts)? And then, how is this time measured?

Is it about time?
It really feels as though this idea of light/heavy follows is about response time. And this idea of ‘response time’ is separated from the idea of ‘time’ in a rhythmic/musical sense. A beat is a beat is a beat. The band sets the ‘time’, and if a follow is keeping that time, then they are always ‘in time’ and never ‘too late’ or ‘too early’…

Unless it’s all about responding to the lead. In this case, then it’s not that follow is too late or too early, but that the follow is not keeping the same time as the lead. This is a) bullshitly control stuff, or b) both partners neglecting the music, because we both have a responsibility to take care of the music.

Or is it about weight, mass?
But if it’s not about time, then is it about actual physical weight? That seems weird, because as a fat chick, I can easily make my hand float in my lead’s hand to ‘feel light’. It has nothing to do with my physical body weight.
Even so, I don’t think that the actual weight of a hand (or a body) is the issue, as we aren’t dead weights, we are active bodies, moving ourselves. Unless leads are asking follows to be dead weights physically wrenched around the floor. But that’s dumb.

Or is it about touching someone?
So perhaps it’s meant to be a way of talking about connection, in the physical and emotional sense? ie the difference between a limp hand that’s just being held by someone else, or a situation where two people are actively holding each others’ hands?

I’m down with that final scenario: when we dance with someone, we _both_ hold each others’ hands, and we both hold each other in our arms. Including follows. We are actively present with our partner. We are here, now.
But even here, we have moments when we aren’t 100% on. When we’re tired, or laughing too much to stand up properly, or when we’re holding our loved one, or … etc etc etc.

Can we just throw this term out the window?
Again, I think that I’m most interested in the idea of partnership as active, responsive, ever-changing, mutable. A ‘light’ or ‘heavy’ partner sounds like a fixed state. I don’t want to be a static or fixed state. I want my partner to know how I feel all the time, and vice versa. Because this is communication, not a leader giving follows directions.