Grammarly can't be compared with AI text models because Grammarly only helps you rectify what you have written and it doesn't write everything itself most of the time, it won't even correct wrongly constructed sentences but only misplaced words or wrong spellings and stuff. I use Grammarly as well because it's a useful tool that helps you find small mistakes in what you write that you might not notice normally. However, what I write is my own thoughts and it is exactly what I want to write unlike AI-generated text which is not what you think but everything is generated by itself.

So tools such as Grammarly aren't comparable with AI language models such as ChatGPT, and people using Grammarly or related tools are not doing anything wrong, in my opinion.