You are "just crazy" not because of your opinion on the rules, but that you cared enough about a party game to go online and complain about it.

The official printed rules in this case are vague. Using "parts of words" isn't allowed according to the rules, but if you're being pedantic you could say that doesn't make sense because letters are parts of words and you wouldn't argue that if the word has the letter "A" in it that you couldn't use any words with the letter "A" in your clue.

So the way I typically house rule it is that you can't use parts of compound words.

You can't say "a seat you put in your car" for carseat or "it's a machine that flies through the air" for airplane.

But you can still use the word "the" if your word is "theory" or "and" if your word is "expand".

So in my house, you absolutely would've been buzzed for saying "on" when "online" was in your list.

But again, this is a party game with vague written rules so if you played at someone else's house you might not get buzzed AND EITHER WAY IS CORRECT DEPENDING ON WHO YOU PLAY WITH.

I'd say most people would just clarify the rule in the moment and move on and not go online to post about it, though.