Although often portrayed as moderate groups in the press, major militias supported by nations like Turkey, Saudi Arabia, and Qatar with money and weapons are some of the most extreme.
The recently killed leader of Jaysh al-Islam for instance has often talked about the need to, "cleanse Shaam of the Filth of Rafidis & Rafidism," and, "filth of the Majoos," referring to Shia as, "despicable & pitiful though history."
Ahrar ash-Sham leadership, past and present, have close ties with al-Qaeda-- as well they've cooperated on many occasions with al-Nursa Front, the al-Qaeda affiliate within Syria-- something common with all major Islamist groups supported by these govs, and widely known.
Supporting groups aligned with terrorists is no different than if you gave them guns directly.