Except that the very point of a general purpose computer is that, to use your analogy, your car can spontaneously sprout parts and reform the chassis as needed. Aluminium frame with a pair of wings and four jet engines one week for that overseas trip, a heavy duty frame with a winch for the construction job on Friday, a napalm launcher for fighting kudzu in your front yard (a stretched analogy, but you can see where I'm going with this).
All of this is enabled by software, which costs nothing at all to replicate unless it's restricted via copyright law. This is very much unlike every other hobby, where specialised tools cost money to duplicate.
I wish it were just a matter of software. It would be nice if my iPad could magically have a GPU as good as my gaming PC or my gaming PC could become a 12" tablet with a 10 hour battery life.
All of this is enabled by software, which costs nothing at all to replicate unless it's restricted via copyright law. This is very much unlike every other hobby, where specialised tools cost money to duplicate.