The grammar check on Windows Word sucks

Here is an example of something I typed in to test it:

My monkey are a good bunch of monkey.

According to Windows, there is nothing wrong with this sentnce. Clearly it was programmed by a drunk four-year-old.

That is funny, but the reality is that grammar rules are incredibly complex with exception after exception. Teaching a computer a language is tremendously difficult.

(By the way, my copy of Word suggests changing the "are" to "is." If I do that, it's fine )

There is something wrong with that? lol

I want to know why he typed that in the first place

To test the grammar check, of course.