I was curious why one developer would provide 2 separate apps which provide shortcut actions (why not combine everything into 1 app?). It seems that Actions is a free app on the App Store which only includes actions that Apple will allow. However, Shortcuttie is a paid app which is not on the App Store because it includes actions which Apple would not allow according to their rules. A $6 one-time purchase for one user with unlimited computers is a great deal given the list of actions you get.
I can already do some of these actions with AppleScript and the command-line, why use this app?
Yes, but the app packages these capabilities into maintained, ready-to-use actions that integrate perfectly with Shortcuts. This lets you focus on building workflows instead of writing and maintaining scripts.