Because UPBE at this moment is light years ahead of PBE. I just added doc for Spotter, Dark Theme, and the new Nautilus icons.
If any of you wants to fix something on UPBE and does not have the confidence to do it directly , because you dont understand Pillar or you dont feel confident yet with Pharo you can still help me tremendously by adding your comment , your corrected text or your addition documentation as github issue here and I will put it in the book ASAP.
https://github.com/SquareBracketAssociates/UpdatedPharoByExample/issuesI will be resolving at least one issue per week from now on to make sure that UPBE is being pushed forward and remains by far the most up to date documentation of Pharo anywhere in this universe. But I cannot guarantee for other universes.