From that very article:
... if labels can't agree to make their videos available to both the free and premium tiers of the subscription service.You need only look at the Amazon Prime Music service as an exemplar, take an artist, make a couple of recognizable hits available for 'free', and the rest behind the service paywall. That is a pretty classic and well used content service feature for attracting new customers, only the content service decides what to give away for free, and what to charge for, not the artist. And if you read closely the original article Zoe said she had to put it on Google's service at the exact same time she did anywhere else. This is a huge loss in marketing leverage for a small artist because she loses the ability to have a special "fan release" that she can get out early to fans to subscribe to her own version of an affinity service.
So lets say she produces an awesome track, and her fans are all abuzz because they hear it first. It pulls people on the edge into the fan subscription service.
But with this arrangement all of that marketing leverage is ceded to Google. They might decide to put her best paying track on the 'free' side to highlight great indie artist tunes on the 'pay' side. She loses her best source of revenue and Google gets to push some people over the edge into paying for their streaming service.
Artistic content, whether it is games, movies, music, or books, has a strong 'freshness' peak in value when it first comes out and then tapers off rapidly. Collecting that value is fundamental to the economics of information, that is why there are "exclusive" stories and "sneak previews".
Google is requesting that artists cede that value over to them in order to participate on Youtube. In my opinion, that is an exceptionally high price to pay.