

Except it automates the steps you’d have to take to inspect and edit the script, if needed. Also, PKGBUILDs are much nicer to read than just plain install scripts. And, of course, it actually builds a package, which is then installed, so it’s not only tracked but can be updated like the rest of the system.
I’d say that yay encourages checking the PKGBUILD or its diff more than the average “curl xy | sudo sh” instruction, but considering most people see yay just as yet another package manager, instead of an AUR helper, that’s probably true for most people