The idea of newsletters is stupid. I need to open them in email, which is not where I read news. We solved this problem ages ago, it's called RSS. Provide good full-content RSS feeds.
If you must persist with newsletters, don't put a full screen flyover nagging me to sign up for the author's newsletter as soon as I've visited the page. How am I supposed to know if I want the newsletter when I haven't had a chance to evaluate the content? At most, put a static non-JS signup box at the end of the post.
The idea of paid blogging is ridiculous. Web hosting is free these days. Nobody is writing blog posts for 40 hours a week and making a full-time income from it. There is no cost to blogging, so there should be no charge. Paid blogging is a non-business model.
There is also an attempt to "legitimise" bloggers with these sites. "I'm a professional blogger, follow me on Medium". No, you're just another person in tech like me. Your blog is no more or less important than mine. At best you're writing things you hope are useful. At worst, you've devolved into a "content creator" making "content" for the sake of it (or for subscriber begging) like so many vapid YouTubers.
These sites seem to imply their content is somehow "premium" or better than the rest of the internet. It isn't. There are many (free) blogs which are way better than every Medium or Substack. I see many poor quality posts on these sites which reduce the overall value of the site. The quality control necessary to make the site curated would negate the appeal of the platform.
I feel if someone has something worth saying, they'll probably spend the minimal effort setting up their own blog to say it, and build a legitimate subscriber base from quality, not from some paid or implied quality by having their blog on a certain domain.