Duplicate word removal seems like a naive, coarse grained method to improve writing style.
Smells like the high school trope of throwing a thesaurus at your essay and hoping for the best
Uncritical duplicate removal, yes. But I edit a lot of work and duplicated words are one of the things that I see time and gain, really dragging writing down. IMO, removing duplicates is one of the cheapest wins, a very easy way of making improvements so long as you do it at all reasonably.
It doesn't even find inflections, such as plural/singular. But as a writing tool, it can only lead to contrived constructions that seem to be the realm of sports journalists: "The multiple medal winner" ... "Last year's 500 meter champion" ... "The Londoner" ... "The former law student" ... when referring to one and the same person during a race.
I do like that it lists them on the side, and allows you to remove them.
Someone commented something similar on reddit a while ago, and it is a very good argument to be honest. Still, you might find some situations where the tool might be useful and it's already deployed, so people can use it if they want
ChatGPT: "Are any of these sentences repetition of each other"
Most educational literature from the US are rife with sentences that might not be verbatim repetition but most certainly say the same with a different word soup.
Still, sometimes recognizing duplicate words points out some bad/imprecise wording where you're repeating yourself and may not like that.
I find myself using the "edit" feature on comments online a decent amount to catch/add things I only found when reading it back in complete form.