Why didn't the Republic use a Droid Army?

Why didn't Darth Sidious use a droid army for the Grand Army of the Republic, there are clearly huge economic advantages. 2nd Channel:    / @generationtechshorts   Follow Generation Tech on Instagram:   / generationtechofficial   Follow Generation Tech on Facebook: http://bit.ly/GenerationTechFB Latest Videos: http://bit.ly/LatestGT Popular Videos: http://bit.ly/GTPopular Please help our channel by becoming a Patron: http://bit.ly/GTPatreon Follow our Host ALLEN XIE YOUTUBE    / @thebeardedasianman   INSTAGRAM AXIEFILMS TIKTOK AXIEFILMS FACEBOOK   / axiefilms