Publishing a website is not permissionless. You have to get a public IP address and register a domain name with an ICAAN provider, and various ISPs have the power to block your site. Actually promoting your site, scaling your site, integrating with common services, require more centralized servers, they're just just more implicit and you can choose from multiple providers (e.g. AWS or Azure). But you can choose to post to Facebook or Twitter.

The problem isn't centralization. It's centralization through a company which exerts too much of its own influence and censorship and monetizes your usage for its own benefit. Plenty of centralized databases allow free speech and don't seem to monetize your data: look at HN or if you're more radical, 4chan.

Idk if all centralized services are doomed to be corrupt so decentralized is the best we can do, like all monarchies are doomed to be corrupt so democracy is the best we can do. But unlike monarchies that hasn't really been shown. Maybe if someone invents a more efficient way to serve decentralized data the web will transition, but until then most decentralized services are most useful only as a backup to centralized services.