Perhaps we should switch from entry to usage by default? iirc the reason I didn't use usage in the past (which upgrading to Babel 7) was that (a) it was more buggy then, (b) it was harder for people to opt out if they didn't need to use a polyfill at all.
However since then, I'm presuming the bugs have been worked out solving (a), and we now dynamically set it to false based on whether core-js is found, which resolves (b).
Either way we should probably also now replace the @babel/polyfill references in the docs with core-js.
The description of entry vs usage can be seen here.