Someone who engaged with a post about the problem you solve has raised their hand in public. They do not know it counts as raising their hand, which is exactly why the reply rates hold up.
Why this pool converts
Two reasons. The person has demonstrated interest in a topic rather than matching a firmographic guess about interest. And the opener has somewhere honest to start: you saw them engage with a specific post about a specific thing, and that is a normal way for one professional to notice another.
The pool is small compared with a cold build. That is the trade. It is meant to be run alongside cold volume, not instead of it.
Whose posts to use
Your own posts give you the warmest and smallest pool. The posts of creators in your space, where your buyers gather in the comments, give you a larger one that is nearly as good. Both work through the same skill; the second is where most of the volume comes from.
Discovery only
It reads public reactions and returns people. It never messages anyone, never connects, and never writes to a profile. Everything downstream, enrichment, verification, qualification and copy, is a separate signed-off step.
Runs well with
Skills compound. These are the ones we usually install alongside it.