It is fascinating to watch the disaster of YouTube channels. From the usability point of view it is an utter failure and it is hilarious to see how attempt to improve an otherwise simple system lead to its complete dismantling.
But first, let me tell you about what's happening to YouTube content this days.
Proliferation of side channels. YouTube rolled out its recommendation system that has a 24 hour sliding window. Content creators quickly figured out that there is essentially only one video per channel per day that gets recommended for the viewers. The ones producing more videos per day created side channels for extra videos. Because publishing 5 videos to 5 channels gets way more viewers than publishing those same 5 videos on one channel.
Video slicing. On the other hand, YouTube short video push started to reward content creators for pushing many small videos. So the content creators who were created 40 minute long video started to ADD twenty 2-minutes clips to accompany the main video.
Those two trends completely destroyed the subscription system. Consider a user who liked a video and wanted to subscribe to that content creator. Now they can't just click the "Subscribe" button, because that'll only give them a portion of the videos. They need to also read the YouTuber's profile page to see the list of their channels and hit the "Subscribe" there as well.
On the other hand, subscribing to any channel creates a lot of "noise" of duplicates in user's feed. Consider CBC News for example. They have "The National" news issue that is roughly 40 minutes long. It is a perfectly valid use case to follow it to stay on top of the news. But anything CBC-newsy gets published to the same channel. Mostly a swarm of 2-minutes clips from the main news program.
The system of incentives for content creators lead to a situation where YouTube Search and Recommendations are the best ways for any regular user to consume the content. The "Subscribe" feature is completely broken and useless.
I see content creators asking viewers to subscribe in every single video and being still baffled by the statistic that two thirds of their viewers are not subscribers.
Frankly, the "channels/subscriptions" feature is super simple and there is nothing wrong with it. It is the incentives created by more complicated and convoluted (AI!) features that devoured it.
For some reason I do not think YouTube product design team is even aware of the problem they have created.