No AI can ever take the place of a human in doing the fine-tuned work that only a human can do. It is a myth to believe an AI can ever replace a human in writing or performing any other artistic skill, or evaluating it. Grammarly cannot even perform the very simple tasks without proper programming. For example, Grammarly doesn't even know how to spell Grammarly.
So, you are correct, the blame is not with Grammarly. One cannot blame a machine or a program. It is always the humans behind the machine or using it who are responsible.
Thanks for reading and taking the time to respond, Shira, and Happy Holidays to you and yours!