Source
KISS principle
The design rule 'keep it simple, stupid', noted in the U.S. Navy around 1960 and commonly credited to Lockheed engineer Kelly Johnson. It holds that most systems work best when kept simple.
Little is known for certain here; this background is thin and may be revised.
References
Quotes (1)
“Keep it simple, stupid.”
— Kelly Johnson (reported), Reportedly coined at Lockheed Skunk Works; attribution per Wikipedia