Inwardly, Prue had been waiting for the defenses, the implausibilities to come out of Piper's mouth. Prue knew her sister well and knew that while fighting demons was basically what they'd done as the Charmed Ones anyway, this wasn't so different. But grasping the fact they were in a parallel universe would be harder.
"No, you can't just blow them up because in this world, demons don't actually have bodies of their own. They possess innocent people that we don't want to kill. Thus why the exorcism and Devil's Trap. Yes I know it's more work than just simply blowing them up or vanquishing them, but we have to think of the innocent people they're possessing. So basically if you ever see black smoke moving at a fast pace, that would be a demon looking for someone to possess." She hoped Piper would accept that because more explanation further than that and Prue would basically just be bull shitting her way through it. Even with being here as long as she'd been, there were still things she couldn't explain well.
"I know, Piper, believe me, I know you want to go home. But you can't. We're all brought here for a reason to help in this fight. You might be sent back home at some point, I've seen many people come and go and come back again in the time I've been here. Just trust me on this, nothing will happen at home until you are back there to take care of it, all right?" Just like Prue herself wouldn't actually be dead until she went back, which is why Prue never wanted to leave this place. She didn't want to die. She finally had everything she'd ever wanted in her life. She was set to marry the man of her dreams, she had the possibility of having two beautiful children with him. If the Seal sent her back home now, she'd lose it all, and she didn't want that. Prue absolutely refused to end up like their mother.