Why move from one corporate entity to another? Substack will end up going down the same road in time. Get your own domain, fire up a CMS and start publishing on something you control and own.
In this case, it's even harder because it's about maintaining a website synchronized with a mailing list.
Make something open source and ad-free and they'd all run to it, I'm sure.
I agree, so maybe we should work towards making it easier for them.
I was thinking about spending my Christmas break fixing Friendica bugs, but now I'm suddenly thinking about building my own ActivityPub blogging platform (though no doubt one already exists). But of course that's not going to be enough; it needs to be trivial to deploy and host, at little cost. I believe many cloud hosting providers have a free tier. Would be nice if something like this could be easily deployed there. Create a tool that sets the whole thing up, handles the DNS name, the payments, and deploys the site.
In fact, it would be nice if ISPs offered something like that for free with your internet connection, to finally do justice to that 'S' in their name.
So much early web lost from URLs like http://www.myisp.net/~username/
Users can continue authoring on those platforms but can begin promoting their own-domain version and gradually move their users off.
I know sometimes there is a project that looks good but the maintainers are impossible to get along with. Thus there is sometimes a need to start over. Most of the time though what platforms need is more people to help out: fix bugs, write documentation, translate the UI, run UX tests. That is all the thankless unseen when it works work that makes good commercial projects more polished than most open source projects.
It's quite weird to see people fawning over the latest startup blogging platforms in 2022.
While people have been migrating to/from medium and substack, wordpress.com has been here the whole time, and it's still quite OK. The killer feature it has, of course, is that because it is open source you can export your data and run it yourself should things go sour (or if you just outgrow it).
Whatever features substack/medium/whatever closed source platform may have that you think you really need, the anti-feature of lockin is not worth it.