Marriage processions disrupting traffic and blocking way of ambulances is a common scenario in our country Should this be allowed?

Nope!

Not at all it should not be allowed but uts the local public fault and administration should take care of this.

While allowing them to play loud music and burn crackers they should also write in written that  no harrasment should be done to any one in public plzce and specially no blockage of vehicles as it makes huge transport issue.