I walk up to you on the street and suggest you give me a dollar.
vs
I walk up to you on the street and take a dollar from you by force.
Youtube is a platform, in order remain a platform it MUST remain neutral. You cannot have an open forum with bias. There are certain mutually agreed upon rules, (no nudity, extreme violence, etc.), those limitations are more than enough to handle the vast majority of "negative" content.
I whole heartedly disagree that we need a bias towards positivity. Who determines what that definition is? Something you see as negative, I might happen to enjoy. If Youtube begins to censor itself in that way it is no longer a platform and is now responsible for ALL of its content.