You have given the answer already in the bold part.
If people don’t find any religious difference they’ll find racial or class differences to fight over.
The differences among different schools is a blessing for those who want to follow Islam rather following their desires. If you look at the history, there were no fights among the four traditional schools of sunni islam that’s why I stick to them instead of dividing further into different schools/sects, that’s why I started the thread if we need more fiqh.