That works when you have one container. When you have 200 and fifty databases and four identical environments (prod, qa, staging, dev) and so on it becomes a lot more error prone. These systems exist for those use cases.
Granted even with one container and a single DB I found terraform useful as I don't have to fiddle with whatever DB, container, etc. settings there are every time. I also prefer to not have to memorize or figure out a UI I use once every other month. Too many UIs across too many things.
Your point makes totally sense. Though I also like to be able to bring up (and destroy) my servers, with a single command, when needed. Going through the same ui every time is a little annoying.
Granted even with one container and a single DB I found terraform useful as I don't have to fiddle with whatever DB, container, etc. settings there are every time. I also prefer to not have to memorize or figure out a UI I use once every other month. Too many UIs across too many things.