I suppose you neglected to read all the responses. Your argument is as silly as "If my box running windows <insert version here> can't read ext3 partitions? how can it be called a computer" or "If <insert statement here> can't run Safari, how can you call it a computer".
The (in)ability to open a particular file format or do OS-specific tasks doesn't (dis)qualify a machine as a computer.
In fact, by default, stock Windows laptops can't open excel spreadsheets either without first installing (or having pre-installed) microsoft office.