When people are producers they don't like deadlines but as soon as they are consumers they demand them.
Go build a house and you'll be constantly asking "when will it be done" and "whenever" isn't acceptable to you.
Order something from Amazon and "it'll arrive whenever it arrives" isn't acceptable to you.
Sell some stocks and ask your broker when you'll get the cash and "whenever, in a few days, not sure man, asking me about dates really takes me out of my Flow State" doesn't sound so great.
We want deadlines. We want to know when our iPhone will be repaired, when our drycleaning will be done, when our children's schooling will be done for the day, when our plane will take off, when our car repair will be done, when the movie will start, and so on.
I always find that these kinds of articles can too often come across as "deadlines for you, but not for me" if they don't really grapple with that reality and try to come up with explanations for the dichotomy.