This is true, but I don't think your point entirely fair either. Zig's design lends itself to writing this style of code. In contrast the usual way(s) C++ is used encourages code that makes these types of optimizations hard/impossible. In practical terms, if you wanted to write fast software, the ergonomics of the language allowing you to use the desired architecture matter a lot.
(Also, you're replying to the primary author of Zig and presenter of that talk, if you weren't aware.)
I am not sure it is comparable: the self-hosted compiler uses a different architecture [1].
[1] https://vimeo.com/649009599/7f1fda43ff