Yeah and the 13k are caused by whom exactly? Definitely isn't US troops shooting up civilians for shits and giggles. Mostly local insurgents killing their own people.
If we stood by and did nothing a lot more would be slaughtered, exactly the situation were seeing with ISIS. If the western world stood by, you'd see a genocide against the kurds, yazidis and shiites.
The casualties of the Syrian civil war is already 150k and displacing MILLIONS of people
https://en.wikipedia.org/wiki/Casualties_of_the_Syrian_Civil_War
This is exactly what happens when you don't intervene in sectarian violence. People seemed to fucking forget Assad gassed his own people and the were clamouring western governments for intervention during 2011-2012. Or would you have everyone standby because omg civilian casualties will happen
welcome to fucking war, it ain't pretty and it's worst than hell. Remember the last time the west decided to go 'meh' on a conflict? Yeah Rwandan genocide happened.
If the western governments wanted to really glass Raqqa, they can easily do it. That city can be flattened in a day if it was deemed necessary.