I agree with the premise of the post title, but less so with its content. Social media is absolutely a walled garden, and has been chipping away at the open web for a long time now. But part of that is the fault of bloggers themselves. In the late 2000s, comment sections became overrun with spambots posting ads to fake Air Jordans and Gucci handbags. Site owners could not (or were unwilling to) block the deluge, and moved discussion over to Facebook, which hires moderators and had better anti-spam features at the time.

Result: they began posting more on Facebook, because of its network effects, and because a large portion of the human race was already there.

WordPress alone isn't the answer to bring back a web-centric (as opposed to walled-garden) model for publishing. What is needed is, as mentioned before, network effects. So things like Web Mentions, small features that link different sites to another, sort of what web rings used to be back in the '90s. And correct me if I'm wrong, but Wordpress.org can take the same approach that YouTube and others have, can they not? BlueHost, HostGator, GoDaddy can as well.

Going all the way down the supply chain, you may just be better off hosting a website on your own server. And if you're at that point, you likely have the ability to use something that's much more lightweight and fit for purpose than self-hosted Wordpress.

Let's not forget that social media networks are private entities and have the right to remove or block any content that appears on their "property". If you fall afoul of their sometimes arbitrary moderation guidelines, that's unfortunate. But it's not unreasonable; there was never any promise made that your content would be allowed to stay up indefinitely or even at all; you are a guest on their platform, just as a commenter is a guest on WPTavern. You can vote with your feet and leave if you don't feel that you're being treated fairly.