English has so many meaningless grammar rules.
That's the reason even native speakers often make grammar mistakes.
Everyone can understand what >>978 says but at the same time it is clearly grammatically incorrect.

Making grammatically correct sentences is difficult, but writing naturally is far more difficult.
That's the reason why many Japanese speakers struggle to master English.
I've mastered reading and am nearing perfect in listening,
but I don't know when I can muster writing and speaking.
It could take another 10 years or more...