Lets speak the truth and say the preaching work designated by the WTS had everything to do with proliferating the literature the WTS published.
The established American government made that all possible without controls, regulation or taxation.
They essentially went about marketing the gospel of Jesus in their own unique and self serving way
Sure it was a tainted commercialized version of the Gospel of Jesus but it worked, there are a lot of people who never read the bible carefully and the WTS leaders accepted and self assumed that.