This doesn't seem like a move that was made for the benefit of writers.
I found Medium through free, high-quality articles, and eventually converted into a paying reader. And as a writer, I liked that I got to earn a commission from my work while also getting to reach a wider audience who weren't subscribed to the platform.
These changes (specifically, the paywall) might lead to more paid subscriptions, but will minimize the overall reach and engagement of stories that are behind the paywall.
As writers, we are now essentially forced to choose between giving information away for free and maximizing our reach, or getting paid for our work at the expense of lower visibility.