A browser is like the blind men and the elephant:
JWZ wandered in the dark until he reached up and touched its rectum. He said, "I think it's a a source of great knowledge, let's expand it to do email and calendaring."
Brendan Eich ran into its cock face-first and said, "whatever it is, we need to stuff Scheme into it, but since I'm not allowed, fuck you all: meet Javascript."
Bill Gates reached up and touched its sweaty scrotum and said, "let's rebuild our applications and desktop ui on it."