No one prevented peaceful assembly. Shaheen Bagh is the best example where protestors have captured a public road illegally for 60+ days and neither the Government nor the Police are doing anything about it. Police and Administration only take action against rioters or those who indulge in vandalism of public property. The Deputy Commissioner of the local district gets first hand information on everything that happens in the district. The DC knows beyond doubt if the gathering is going to be peaceful or violent. We have highest levels of intelligence gathering and that has only increased and strengthened manifold after various terror attacks. Hence why the Supreme Court doesn't take the Centre to task neither does the High Court take the State to task over imposition of Section 144. The judges instead just give a rap on the fingers. That is because the administration has all details about the nature of protests and can provide adequate proof. If you really want to understand all this you should spend sometime with retired IAS officers and if they get to like you will tell you the workings of the system. You can't fool the administration into thinking that you can riot in the guise of "peaceful protests". The administration has various ways of intelligence gathering and knows exactly what the outcome of the gathering would be.

Apart from better policies, they also need enforceable ones, where local law enforcement is empowered to deal and contain where necessary.