Fans were desperate for FaZe to have an era in 2017 because they looked amazing at some of their earliest events, but it never really happened.
They choked repeatedly in finals and didn't win anywhere near enough trophies to have an era.
NiP, Fnatic, Luminosity/SK and Astralis are the only teams to have eras. Others may have won some big events and even reached #1 ranking for a while, but ultimately that doesn't count for much in the context of CS:GO history. At least if the team was an underdog, their success might be remembered (like Gambit) but most people will only remember 2017 FaZe as being underachievers.