I... don't want to seem like I'm trying to make arguments here
but I do think I should maybe defend myself? I included the part about the Korean author based on one of the original poster's previous replies that said they had many ideas but didn't want them 'wasted' on their current level of writing ability, since they judged that their abilities could be enlarged upon. I was trying to say that it's alright if they save up their ideas for later until they feel ready. :D
Also, as for your point about how you should only write based on your own ideas, I'm pretty sure the original poster didn't ask for fully formed ideas to write off of but one-line prompts:
...which would basically mean that they end up formulating their own ideas anyways. I've taken creative writing courses before (not that they should be the standard to learning how to write, of course) where they set you into writing exercises and full projects basically based on similar prompting. If you want to write something you really wanted to your whole life for that class, you can, but it's just as valid to use those prompts and begin writing.
Ahhh anyways, I'm not trying to say that your way is invalid or anything-- it's one completely viable way to go about things-- but my point is that it's not the only way. I really think choosing a temporary idea to write about can be very beneficial because, due to less emotional attachment to the idea, you can be less afraid of failure and thus more experimental, which is where a lot of growth can happen. But as someone else in this thread said, to each their own.
+ To the original poster (sorry for lowkey? kinda? having a sort of debate thingy on your thread!), here are some exercises from a previous creative writing course that you might play around with, too! :D
1. Write a short story with only inner monologue, none to minimal spoken dialogue
2. Write a story that only consists of written communication (letters, notes, texts, etc.)
3. Write one scene, then tell the same scene from another point of view (first person VS third person)