Clipboard paste is the blunt instrument: copy the transcript, send a paste shortcut, restore whatever was on the clipboard if the app is well behaved. It works in many electron apps and browsers, and it can clobber a clipboard the user cared about if restoration fails. Simulated keystrokes type the string as if each character were physical input, which some terminals and games expect, but it is slow for long paragraphs and can trip input methods. Accessibility APIs, including macOS accessibility attributes, can set the value of a focused element more directly when the app exposes it.
Failures look like 'dictation does nothing' even when recognition succeeded. A secure password field may refuse paste. A remote desktop may swallow synthetic keys. A browser may steal focus. Per-app overrides exist because there is no universal injection that satisfies every toolkit. Permissions matter here as much as for the hotkey: an OS that blocks controlling other apps will transcribe into the void. Debugging injection is debugging the focused process, not the speech model.