Indeed, many applications I would expect to prevent sleeping (some audio playback ones, games, etc.) don't implement this. I assume it's a case of Apple's APIs changing over the years and not everyone catching up/caring. At one point I had downloaded Amphetamine[^1] but it is much nicer to just use the terminal here.
The "newest" and still supported low level API is almost 14 years old: https://developer.apple.com/documentation/iokit/kiopmasserti... https://developer.apple.com/documentation/iokit/kiopmasserti...