Zawinski's Law

Every program attempts to expand until it can read mail. Those programs
which cannot so expand are replaced by ones which can. Coined by Jamie
Zawinski (who called it the Law of Software Envelopment ) to express his
belief that all truly useful programs experience pressure to evolve into
toolkits and application platforms (the mailer thing, he says, is just a
side effect of that). It is commonly cited, though with widely varying
degrees of accuracy.

