It's just insane that you need Amphetamine, homebrew, iStat menus, and a dozen other 3rd party tools to do what should be part of an operating system's job anyway.
It is part of the operating system. You can either disable various power-saving measures. Or use the built-in shell command caffeinate. Or run a muted video looping in the background.
As a teacher, I was often in situations where a lesson would go on for a while with no computer interaction, and another teacher recommended Amphetamine. It worked well and I never discovered the shell command. I actually tried for a bit and never discovered a GUI option. Do you have a link handy?
You’re being downvoted for oversimplifying what this app does as well as the combative tone. As GP said, on Mac you can turn off sleep timer permanently in the OS settings. The app in question let’s you keep awake for the next N minutes/hours so the “keep awake” setting change isn’t permanent. It makes sleep-settings workflow much easier. It’s simple but worthwhile.