The chemical attacks assad launched are in keeping with the cynical mindset of a tyrant, think Stalin or Hitler. What these types do often does not make sense to sensible people and never to ethical people. Being cruel and getting away with it empowers them in the eyes of their supporters and is designed to break the will of the opposition. If no one can help the innocent, despite how brazen the crime is, then why have the will to fight back. Submit. This how you break and defeat an enemy when you're unconstrained by morality.
Many people heard of the Holocaust as happened. They refused to believe it. It was just propaganda, skeptics said. But only a fool or a malicious person denies it now. Sometimes the ugly and irrational truth is true.
Please tell me you don’t believe half the stuff you just wrote. The Syrian Army has taken large swaths of territory back from Isis & al Nusra, including Palmyra, Deir Ezzor, Aleppo, & Kawkab. True, they don’t differentiate which terror groups they attack, but attack they have, and “Isis” has suffered mightily.
Russia also bombed the crap out of Raqqa, but you knew that.