Explain why I should use Substack

I read a number of writers on Substack. https://theupheaval.substack.com/p/the-reality-war
https://wrathofgnon.substack.com/
https://venturewithreality.substack.com/

And others.

But I just can’t figure out why they would use Substack versus their own domain and servers. I can create a newsletter, manage emails, charge for subscriptions, everything that Substack can do (as far as I know) and I control it all.

There’s a risk WordPress will prevent me from using their software somehow, but that wouldn’t be a deathknell to the project here.

Explain why I would be well served to use Substack.

I just don’t get it.