This is far from life and death stuff, but here goes:
"English" rules of grammar are not known for their logic or even their own internal consistency. Thankfully, the days are long gone when writers blindly followed the rules. But, every now and then, I'll read something and think, "That doesn't sound right" and, sure enough, if I check out my old school English grammar books, it ends up being right.
Classic example: If I am writing in "speculative' mode (i.e., putting myself in your shoes) it is perfectly okay for me to use the plural form of To Be, as in the following sentence: "If I were you, I'd leave". Little wonder, we keep making grammatical mistakes - some of these rules go back centuries.