Why can't protestants unite to form a single church,instead of 30,000 churches,isn't unity strength?

Jesus said-"you be one(united),just as i and the father are one".Why don't you practice what you preach?I ask this because i understand certain practice of catholics like using images/statues of 'saints' for prayer,worship and bowing infront of them is idolatry.This is how the practice of 'intercession to saints' is done.Bible makes itself clear many a times that we have only one intercessor b/n mankind and god and that is Lord Jesus Christ.And so you have credibility in what you stand for,why not unite so you wont lose that credibility.I don't want you to unite by creating a priest bishop heirarchy like catholicism,but existing as independent local churches yet united by the spirit of god.