Here's the error without dataclasses:

------
from typing import Protocol

class SomeProtocol(Protocol):
    @property
    def some_value(self) -> str: ...

class SomeClass(SomeProtocol):
    def __init__(self, some_value):
        self.some_value = some_value

if __name__ == '__main__':
    a = SomeClass(some_value="value")
------

Traceback (most recent call last):
  File "foo.py", line 12, in <module>
    a = SomeClass(some_value="value")
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "foo.py", line 9, in __init__
    self.some_value = some_value
    ^^^^^^^^^^^^^^^
AttributeError: property 'some_value' of 'SomeClass' object has no setter


And here it is without Protocol:
--------
class SomeProperty:
    @property
    def some_value(self) -> str: ...

class SomeClass(SomeProperty):
    def __init__(self, some_value):
        self.some_value = some_value

if __name__ == '__main__':
    a = SomeClass(some_value="value")
--------

Traceback (most recent call last):
  File "foo.py", line 10, in <module>
    a = SomeClass(some_value="value")
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "foo.py", line 7, in __init__
    self.some_value = some_value
    ^^^^^^^^^^^^^^^
AttributeError: property 'some_value' of 'SomeClass' object has no setter