There was no ban on setting up new grammar schools for the first 40 of the 50 years during which no one has attempted to do so.
That ban itself was enacted as a tidying up exercise, with little or no coverage or controversy.
If the policy of lifting it were remotely likely to make any real difference to anything, then it would be receiving wall to wall coverage.
But instead, it is receiving practically none.
That fact speaks for itself.