[swiley-gin]

Software is just the smell of other computer users. Some smell nice, most smell terrible, it's nothing special either way. You can rewrite anything in an afternoon if you're in the right mood.

[tmtvl]

Maybe not an afternoon, but any software could be rewritten given enough time and interest.

Although copyright and patents may prohibit you from distributing it.

[swiley-gin]

*prohibit you from legally distributing it (which makes it difficult to profit from.)

Also everyone way overestimates how hard it is to re implement all this crap.