"누구든지 한국어를 배워도 돼요."
Translation:Anyone may learn Korean.
Technically, in English, "Can" and "May" have 2 different implications.
"May i go to the bathroom?" and "Can i go to the bathroom?" while meaning roughly the same thing are not exactly the same and in certain circumstances are not interchangeable.
E.G "The Policeman may come round the corner" and "The Policeman can come round the corner"
The former indicating a degree of likelihood of the action occurring as opposed to the latter statement indicating that the action is just possible.
Does the same principle follow in Korean?
While in English that may (notice my use of the word may ;) ) be true concerning the differentiation of can and may. If you penalize the learners on the simple fact of their misuse of the word "can" it will make the task of learning much more strenuous.
While I can agree to your point you have to realize the English language and the Korean language run by different rules while they both have words that correspond to each other in meaning at the end of the day they don't exactly mean the same thing entirely. Since the use of can and may are so closely used with each other it's probably better to leave both as options.
Also, keep in mind while one word can have multiple meanings in English that same word in Korean could have just one, or even more than the English equivalent, or be used in an entirely different way.
(1) In affirmative sentences, all the -든지 pronouns take on the meaning of Any-.
누구든지* (who/whomever it may be)
= 아무나 (anyone/anybody)
= 누구라도 (regardless whom it may be)
- 누가든지 does not exist. *
(2) 아무도 = Anyone/anybody is used only in negative sentences. It is often interpreted as No one or nobody when the translation of a negative sentence puts the negation on the pronoun instead of the verb.
= Lit. Anybody does not know
= Not anybody knows
= Nobody knows.