Unfortunately, I doubt there's a 'wall team' within Disney that manages everything related to the walls, as great as that team would be to be a part of.
What happened is the wall became a thing a few years ago with guests (Joe Rohde even took notice of the Moss Wall in Pandora before it opened, so it's definitely not a 2018 thing), Disney Merchandise decided to embrace it, the blog jumped in as well, all while the park team had plans to repaint all of Tomorrowland.
These all happened independently of each other, just like the passholders tshirt that featured attractions that were announced to be closed at the same time.