And actually the effect can be negative as, Substack is known to make payment based newsletters, people could avoid those links
I think the only way you can really have a true "free speech" platform is to make it entirely self-serve. As soon as there is algorithmic content discovery, bad actors will attempt to game it to get their ideas in front of people.
I had a couple of decently popular articles. The most popular had about 170k reads before I deleted my Medium account.
Often they do the promotion for you (newsletters, twitter, etc.).
That’s not to mention the medium algo that can pick up on your article and recommend it to others.
I’ve had one post reach 100k+ reads, unlikely that would happen on my own site.
If you leverage their algorithm cleverly, yes. But you still don't own your content or the platform. You're at the same mercy as on Facebook, Twitter, or Google.