Anti-tank guided missile systems were used to great effect throughout the Syrian Civil War. Here is a budget ATGM system being used to destroy clusters of ground troops in the open.
You would think, given a bunch of anti-tank guided missile systems, and an enemy who regularly uses armor to deny your guerilla force the ability to maneuver freely across the battlefield, ATGM systems would be used primarily to destroy armor. In Syria however, that was only the case for the first couple of weeks the ATGM systems were in use by the Free Syrian Army.
After seeing the impact that the TOW systems provided by the CIA had on the battlefield, the rebels started to find new uses for their ATGM supply. While they couldn't always acquire TOW missiles to do the work they wanted, they had no issues getting systems like the 9K111 Fagot missile system out onto the battlefield. Once the cheaper and unchecked systems hit the battlespace, all bets were off.
ATGMs stopped being used primarily for destroying armor, and started being used as an anti-personnel device. Why use a sniper rifle, which is highly dependent on the skill of the shooter, when you could use a wire-guided missile system that had an incredibly high efficacy rate, and required very little shooter skill to reach even more devastating effects?
This video shows members of the Free Syrian Army hitting Syrian Arab Army troops in the open. Throughout the war, I can only imagine the immense pressure felt by Syrian ground troops, who were constantly being hit by super-sonic missile systems they had no counter-measures against.