Comment by psychoslave

If the function is long, accumulate variable along the way, and open intertwined control flow every three lines, no a single function is not at all a scalable way to expose a construction involving many transformations and sources and debugging will be as hard as the control follow depth times number of stacked variable so far as it's stepped through.

With method chaining at each step you have only the complexity of the current method inputs to deal with: that's a far better noise/signal ratio.