Unfortunately as far as I can tell that headline isn't really a very good summary of the situation, nor a generally accurate statement.

Svelte wanted to ditch the need for a build step in testing. Most library authors already tolerate having a build step for multiple reasons, and have no need to go this route. If your builds are too slow, you'd just use a fast compiler like esbuild and reserve the tsc pass for CI/tests and local IDE type checking. (There are still some advantages of not needing a build step, but IMO most people don't mind it as long as it's fast.)

If JS had a type syntax, this would be no issue at all. Unfortunately, who knows if that'll ever come to pass.

As far as I can tell the Svelte developers are not claiming at all that you should abandon typechecking, which is what a lot of people seem to be reading out of this.