Hello. 
Why anyone would want an advantage for this, I don't know. It's nearly impossible to figure out any. Yet, I did. You're welcome. 
Advantages:
✯ Everything would be harmonious, whether it be bad or good. 
✯There would be no such thing as, "picky people."
✯There would be no arguments over social issues. 
Disadvantages:
✯There would not be any variety that shapes communities. 
✯Opinions would be virtually nonexistent.
✯Individuals would be prone to be controlled.
✯People's beliefs would be so similar that they'd become facts to them. 
        
             
        
        
        
Can you provide a picture of what you mean?