I think the idea is that it's better to maintain several functions whose implementations are each linear flow than to maintain a single function that is littere

I think the idea is that it's better to maintain several functions whose implementations are each linear flow than to maintain a single function that is littered with type key checks to turn on and off parts of its flow. It's trading off comprehension of each function by adding some risk that those functions will have shared parts that go out of sync.