From the article in question, emphasis mine:
I put it like this: I have been running since I was about a year old. Almost 40 years! But I cannot for the life of me run a marathon. I am not physically capable of it, even though I can run a few miles in a row. Writing a book is a marathon. You have to train for it, practice, understand your strengths and weaknesses and work hard to overcome them. You need help, feedback, and support, and you need to try many times before you run your best race. Writing a book that someone else wants to read is running your fastest marathon. No one does it right out of the gate, and few writers can expect to have the stamina without rigorous training.
If you want to write a book, do it. Itās wonderful and horrible and fulfilling and soul-crushing all at the same time. But do it because you want to, not because someone suggested it one time. Be mindful of what it fully entails before you start, so you have reasonable expectations and set reasonable goals. You donāt have to write with the aim to get published, and you donāt have to publish with a traditional publisher. There are many options if you just want a copy of your story that you can hold in your hands. Just be careful when well-meaning, though wholly uninformed, people say you should write a book.
This article honestly doesn't strike me as discouraging at all.
It seems to me like there's a lot of emphasis on how hard/unlikely this is because of the sorts of situations the author deals with. Over and over they give the example of someone having been told by a relative "oh! you should write a book!" just because they had a really interesting experience or because they can crack up the family around the dinner table.
That person needs to be told, "no, you can't just slap your family stories down on the page word-for-word how you'd say them and think that will be entertaining to read. This is actually really hard and requires a skill you haven't put any work into developing. If you want to develop that skill, go for it!!! but understand writing a publishable book is more than just relaying a thing that happened."
It's very specifically addressed to people with a casual, passing interest who think that a casual, passing interest is all that's required to put a book on shelves. That seems very reasonable to me!!