Hitler used to gas his own people. Should we have let him get on with it too because it was "none of our business" then?
Obviously, old Adolf was a warmongering [Poor language removed] at the same time but if countries like America and Britain don't intervene when atrocities like this occur, more and more leaders/dictators will see it as an acceptable method of dealing with their own people who don't fit their profile as an ideal citizen.
A full scale ground invasion like Iraq and Afghanistan would probably be a huge overreaction but a tactical bombing campaign that leads to the elimination of that evil [Poor language removed] Assad? I'm all for that.
And Britain/France gave him Czechoslovakia before we entered the war, before giving up most of Europe to the Russians after the war.
Likewise, our intervention in that period caused massive unrest in the middle east, India/Pakistan. Heck, Syria itself was only formed after the English and French divied up the Ottoman empire after WW1.
Do we think less of Germany and Japan because they've had pacifist constitutions for the last 70 years? Has it harmed their development as nations?
If you go back a few years, most in the west thought the Arab Spring was a great thing, yet we've seen it unravel spectacularly in Egypt, and it result in a civil war in Syria.
Not sure it's wise to think our intervention in global conflicts have been unreservedly positive.