Are you saying that by providing a globally available service, they're engaging in vendor lock-in, because otherwise you'd have to build your own globally available and distributed service...? ...yeah?
But if you wanted to run Workerd on EC2 or Google Cloud or whatever, you could...so not really sure how that applies here.
You cannot say you’re the spiritual successor to WordPress, if your software doesn’t support running plugins out of the box on arbitrary installs. WordPress is very easy to host and scale, you only need a basic server and a CDN. A spiritual successor would follow that and also have all the new shiny stuff.