Because linters will not recognise a third party solution. Personally I've written code like:

```

def __init__(self, **kwargs):
    self.__dict__.update(kwargs)

```

and regretted it later when my IDE didn't know about any of the attributes.

This particular proposal is not necessarily the best solution to this problem. Steven's parameters() function or a shortcut for keyword arguments with the same name would also help. But it needs to be something standard within Python. This solution doesn't require any new language features, which might mean it has a better chance than other proposals.