I laughed.

...but in the real world I stopped using Grammarly fairly fast.

First, my grammar is better than their model's grammar. It is particularly poor if you are trying to write expository essays - at the time, even simple constructions like "Money: is that really all you want out of life?" were flagged.

In a month of using it, I don't think I took even one of its suggestions.

Worse than that, though, it seemed to be sending everything I typed off to some server somewhere, and there didn't seem to be any way to turn it off for different sites.

That part is a big deal for me. I would want some serious privacy guarantees.

It's not like spell checking. I thought I was a perfect speller but ubiquitous spell checking revealed a dozen words or so words I had been spelling wrong my whole life, like "pursue". What a revelation!