This is because of the influence of Latin. In that language, the 'kw' sound was represented by 'qu' in words such as 'quis', meaning 'who'. In Old English, this sound was represented by 'cw' in words such as 'cwene', meaning 'queen'. After 1066 and the Norman Conquest, 'qu' began to be used alongside 'cw' and by the end of the 13th century it had replaced it entirely. So, the 'qu' form has existed in English for over 700 years now.
You'll be hard pressed to find a word that is not a proper noun where the Q is not followed by U. Examples are qadi, qibla, qintar, qoph and qorma. They are all variant spellings of other words. Don't know how "firefly" thinks that qwerty is a word, maybe he hasn't noticed the connection with his keyboard. Using a Russian one firefly?