Why do we need __init__ to initialize a python class

Citation: But I can also do

class myClass():
    x = 3
    print("object created")

A = myClass()
print(A.x)
A.x = 6
print(A.x)

No you cannot. There is a fundamental difference once you want to create two or more objects of the same class. Maybe this behaviour becomes clearer like this

class MyClass:
    x = 3
    print("Created!")

a = MyClass() # Will output "Created!"
a = MyClass() # Will output nothing since the class already exists!

In principle you need __init__ in order to write that code that needs to get executed for every new object whenever this object gets initialized / created - not just once when the class is read in.

__init__ is used to initialize the state of multiple instances of a class where each instance's state is decoupled from each other, whereas your second example, without __init__ initializes an attribute that is shared among all instances of a class.