PERFECT Grammar is optional. (edited from "Grammar is optional" because people didn't recognize the hyperbole. My bad)
Sure, you have to have the basic grammar that everyone understands so that your writing can be understood. Beyond that, style takes over. I learned this from a newspaper columnist years ago. He didn't follow the Exact Rules. He made up some of his own, and his writing was better for it!
And so it is with me. I write to be understood and hopefully easy to read, and maybe, just maybe, be entertaining. Grammar is only part of the equation for me.
So what do I tell people? Use these tools (Grammarly, Hemmingway, etc) to become a better writer, and when you feel like you've met your goal, toss them. They're good for the purpose, but will limit you in the long run.