Loss of water, living space, and farming livelihoods absolutely leads to nasty stuff.

https://en.wikipedia.org/wiki/Water_conflict

Syrian massacres are a symptom of protestors and rebels gathering at a certain point and the government using military force and now we are back to square one.

I have read a bunch of them and the massacres are clearly in response to resistance movements so they cannot be the root causes. The problem isn't a trigger happy government that just needs to get it's hand off its weapons and then peace sets in.

If anything, if I had to point to a root cause based on almost no research I would start here https://en.m.wikipedia.org/wiki/2011_Syrian_Revolution and not with some random massacre.