I use the Building Blocks feature in Word to create reusable components for my documents, and for the most part, it's a great, user-centric feature that adds a lot of value to the application for content creators. I wonder why this concept has never been extended to PowerPoint. Presentation creators often need an easy way to add complex, reusable components, such as custom shapes/groups, animations, and even media to their decks. Sure, templates can handle some of this, but I've found in practice it results in bloated templates that often include a bunch of sample slides with common assets that users might want to copy to their own presentations. Building blocks could be added to templates to give content creators a grab bag of reusable assets within the slides they create.
If you agree, I've added a thread to the Feedback Hub, and I'd encourage you to upvote. Thanks!