The reason people say "writing code isn't the hard part" is because the only thing an LLM saves effort on is typing code into the computer. You still have to know what the code should do, and you still have to review the code the LLM generated to make sure it is reasonable. In other words, you still have to do the hardest parts of your job, and the LLM only saves you effort on something which was no real effort to begin with. That is why they are an ineffective tool, because they are helping you with the bits you don't actually need help with.