I use Youtube a lot. I have unsubscribed to certain Youtubers because they release too many low quality videos mixed in with their good ones. Jim Sterling is an example, Jimquisition videos are good, most of his others are filler where he scrapes the bottom of Steam's basement. I do not need all that flooding my subscription feed so I check his videos just once a week as an unsubscribed visitor.
I also do not subscribe to youtuber twitters because those tend to be mostly filled with more low quality garbage--I value the content in high quality videos and that's it, that is all I want in my feed. I might check a twitter directly just to find out when someone is streaming next but very rarely is there anything else worth my attention in there.
If this change results in feed spam that subscribers do not have fine grained control over (like a checkbox to enforce 'only videos') then I expect to be unsubscribing from a number of youtubers.