This is because the Montagues and the Capulets hated each other. If they would have been able to be civil with each other, Romeo and Juliet wouldn't have felt the need to hide their love for each other from their parents. If the Montagues' and Capulets' would have been more supportive of each other, the marriage of Romeo and Juliet would have been public knowledge and Tybalt wouldn't have upset Mercutio because of his rage against Romeo and Mercutio would still be living along with Tybalt, and then Romeo