Google is starting to pull Google+ from other products and YouTube looks to be the first to receive this treatment. "in the coming months" you will no longer be required to to have a Google+ account to create a channel, comment or upload videos. Not yet, but soon™
http://www.theverge.com/2015/7/27/9047785/youtube-ditching-google-plus-requirement
http://www.theverge.com/2015/7/27/9047785/youtube-ditching-google-plus-requirement