It's not so much about blocking as it is about delaying the module waterfall. E.g. a module that did `await new Promise(_ => setTimeout(_, 5000))` at the top would prevent any of its dependents from being loaded for 5 seconds.
In other words, if you put
for (let i = 0; i < 10e8; i++)
// blah
Would top-level await be different?
edit The premise, as I understand it, is that the module itself is treated as the "currently-executing method" for the purpose of the `await`.