The engineers that did that have gone, replaced by newer folks...

As companies get larger, the engineering talent reverts to the mean. The first crop of engineers, that were passionate about it, and made it a success. After they move on, they are replaced with average corp. employee, that joins Spotify as safe/boring job. Hence anything interesting gets removed, and the most boring features survive.

Ps. I was one of the involved on that feature. I didn't write it (It was done in Sweden), but I created one of the earlier demos, (and patents), and that eventually became touch to preview.