The puppet show (which is incredible) builds up how Luke’s sacrifice has inspired the galaxy, but the dialogue I’m talking about suggests that the galaxy hasn’t been inspired and remains as hopeless as ever.
Beyond that, there’s the simple logistical problem. Even if the galaxy is receptive now, that’s a LOT of people and ships to find, recruit, prepare, and coordinate in just a couple hours of “send[ing] out a call for help for anybody listening.”
The dialogue you are referencing shows POE has lost hope. It shows that Zorii and perhaps the galaxy have not:
POE: (sighs) I can’t walk out on this war. Not till it’s over. Maybe it is. We sent out a call for help at the Battle of Crait. Nobody came. Everyone’s so afraid. They’ve given up.
ZORII: I don’t believe you believe that. Hey. They win by making you think you’re alone. Remember? There’s more of us.
Further, removing the dialogue doesn’t solve the problem of gathering such a large force so quickly. You would need added scenes to do that.
Some things are meant for Ascendant, others for fanfiction.