> Google's JS style guide also focuses on JSDoc for the same reasons

Google uses TS internally. Any JS is strictly legacy code at this point. The link you posted even says this at the top:

> Please note: This guide is no longer being updated. Google recommends migrating to TypeScript, and following the TypeScript guide.

Also, Google's style guides are not really authoritative outside of Google. They are for some people, who choose to adopt them as their own, but you really shouldn't point to them as the end-all-be-all argument-stopper. Google has a lot of its own idiosyncrasies. Their C# style guide puts braces on the same line, for example, because Google primarily uses Java internally.