It is still the same in 3.11:

>>> class WithoutSetItem:
...     def __getitem__(self, key):
...         return "foo"
...
>>> class WithSetItem:
...     def __getitem__(self, key):
...         return "foo"
...     def __setitem__(self, key, val):
...         return
...
>>> wo = WithoutSetItem()
>>> del wo[0]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'WithoutSetItem' object doesn't support item deletion
>>> w = WithSetItem()
>>> del w[0]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: __delitem__
>>>