The deploy script failed and the output is gone
It ran, something broke, and the terminal that had the output is closed. Running it again either works for no clear reason or fails the same way.
What it does. Output is streamed and kept, so the failure is still there to read afterwards. It reads the actual error rather than reporting that the script exited non-zero.
Only one person can deploy
The steps live in one engineer's head, so releases queue behind whoever knows the order and the gotchas.
What it does. Anyone asks in plain language, the plan is shown before anything runs, and every step is visible as it happens. The knowledge stops being a single point of failure.
The server is brand new
There is nothing to deploy onto yet, so the first release means an afternoon of setup before any code moves.
What it does. It installs what the project needs, sets up the web server, moves the app across and issues the certificate, showing you the whole plan before step one.
It said success but the site is unchanged
The script exits zero, and yet the old version is still being served.
What it does. It confirms afterwards rather than trusting the exit code: what is actually running, whether the service restarted, and whether the site responds.
Setting up a second environment
A new environment means copying a working one and carefully changing the parts that differ, which is exactly where mistakes hide.
What it does. It copies the configuration on the server and changes only the keys that should differ, showing you a diff of each one before writing.
Nobody remembers what changed
Something broke this afternoon and the only way to know what shipped is to ask around.
What it does. Every action, who approved it and what came back is written to an audit log, so the question has an answer instead of a guess.