Though even with memory it's not as clear as you assume in the context (which is about browser-based apps). Singular C/Zig/Rust program will surely be more economical than a singular in-browser app due to browser itself having a huge footprint. But what if said user has that browser open all the time anyway as probably most users do? What if there are more than one GUI-rich app, and with browser they share most of the overhead? PLs which allow low-level optimizations offer great opportunities, no arguing. But never say "never" until you know what exact problem yiu have to deal with.