a leak instead of a lock
A lock holds the whole bag and opens it at once. That works, and it also makes a cliff: the second the open unlocks, the open sells. Here the bag never closes. It leaks from the first second, and the size of the leak is set by where on the curve you bought.
The wallet that lands in block zero can move 4% of its bag an hour. Nobody has to wait for anybody, and nobody gets a moment where the whole early supply is free at once.