Are you sure about that? Because I’m sure it was a thing back when the new UI was first rolled out, and reading back through the changelogs for the Samsung and Xbox apps in the Announcements section (I only use those two platforms and have been enrolled in the early access since it was initially rolled out so I’m quite familiar with them) would suggest otherwise.
For example in the Samsung updates thread from the 9th August 2019 onwards:
Fixed an issue that caused the app to become unresponsive after deleting a hub from the Home screen
Disabled the option to add hubs to home screen when
Automatic Homeis enabled
Fixed pinned sources occasionally not influencing home screen content when switching between Auto and Custom modes
