Eli5: why do space rockets have all the cables still connected during the first seconds of lift off?

Question

Eli5: why do space rockets have all the cables still connected during the first seconds of lift off?

In: 3479

Answer 1

Because the computer makes sure the engines are all running properly before it will release the hold down clamps. Lots of launches are scrubbed after engine startup but before lift off because the engines arnt running at 100%