Spotlight on macOS most definitely searches files, much of the system is in fact built on file system metadata attributes. (It was original designed by Dominic Giampaolo, who also architected BeOS's file system.)
Recently I discovered that Xcode uses Spotlight in an interesting way — when you want to convert crash logs from your apps into readable stack traces, you only need to place the relevant symbol files anywhere on the disk where Spotlight can find them. No need to import them directly into the IDE.
Not just FS metadata, it can index ID3 tags, EXIF, and whatnot, and it’s fairly extensible, although underused.
Kind of like the underpinning concept of AppleScript and app dictionaries, awesome tech and concepts, but it’s sad to see the promise of the extensible, composable desktop slowly dying.