I maintain that the flexibility in npm package versions is the main issue here.
You still need some out-of-band process to pull upstream updates and aside from a built-in “cool down” (until you merge changes) I see that method as having a huge amount of downside.
Yes, you sidestep malicious versions pushed to npm but now you own the build process for all your dependencies and you have to find time to update (and fix builds if they break) all your dependencies.
Locking to a specific version and waiting some period of time (cool down) before updating is way easier and jus as safe IMHO.
You can vendor your left-pad, but good luck doing that with a third-party SDK.