This grammar point is used to explain or emphasize an action which is made to be the main topic of the conversation. (In the past it was very difficult to get a job as woman), we emphasizing to get a job as woman.
옛날에는 여자가 취직하기란 하늘의 별따기였다. (In the past it was very difficult to get a job as woman)
계획을 하기는 쉬운데 실천에 옮기기란 아주 어렵다. (It is easy to plan things but it is difficult to put it into action).