What’s the RAI behind give to a Thug a +2 bonus to Intimidation check?

@JeremyECrawford What's the RAI behind give to a Thug a +2 bonus to Intimidation ability check? NPC can use social ability check against PC?

— Draconis (@DerynDraconis) June 21, 2016

If an NPC has proficiency in a social skill, it's primarily meant to be used against other NPCs. #DnD https://t.co/LDXcVfXeiZ

— Jeremy Crawford (@JeremyECrawford) June 21, 2016