In my experience you can use a LLM to point out typos or grammar errors, but not to actually edit or rephrase your work.
These will still fall prey to the reason that LLM summaries are bad.
So you didn't try out this specific LLM based tool, but you extrapolate your experience from generic LLMs to judge it? To me that sounds like a hasty generalization .
I just want to genuinely now whether this specific tool might be more useful at a specific applications than generic LLMs, yet here on the lemyverse a discussion like that is impossible because AI BAD. It's a sad and frustrating state of affairs.