There are many other places where using the definite article is very weird in English, but it still requires it in the translation. I guess it's just inconsistently applied, but it's going to get frustrating when it needs you to write out the whole thing and you have to remember which sentences want "the" and which don't rather than what's grammatically sensible in English.
When I said "The breakfast is A egg and coffee", it marked it wrong just for that tiny little mistake, but sometimes, like a recent problem before that, when I said "baname", instead of "banan", because I had to translate "banana", it marked it as correct, saying I had just misspelled that word. Can somebody tell me why that is?
In my experience, Duolingo will allow spelling mistakes as long as what you write is not another recognized word. Therefore, if you write "banama" instead of "banana" it will allow it as "banama" is not a word in English, whereas an input such as "bananas" might be flagged as wrong as this is essentially another word in the dictionary (according to Duolingo) and not a 'spelling mistake' variant of the correct word.
In contrast to "de ontbijt"? In most languages that classify nouns in certain groups the grammatical gender has no strict "why", based for example on the meaning of a word. It is simply a convention you have to learn. Why would it be "de ontbijt" instead?
However, if you want to learn more about Dutch's grammatical gender, maybe this is a good place to start: http://en.wikipedia.org/wiki/Gender_in_Dutch_grammar