I like new UI ideas like the Touch Bar, and I think it was one of the more interesting experiments in recent years.

It had real potential, and apps like Final Cut Pro and Photoshop showed it. But it also had problems: no tactile feedback, no physical Esc key, and it only existed on some Macs, so developers couldn't count on it being there. Apple also added little to it after launch.

That created a chicken-and-egg problem. Developers wouldn't invest in a feature that wasn't universal, and users had little reason to care when few apps used it well.

Plenty of UI ideas fail this way. Good concepts need broad hardware support and strong first-party backing to catch on.