Why "event.preventDefault" onSubmit?

[budodi]

Given the example below:

onSubmitTask = event => {
  event.preventDefault(); // Why this?

  const task = {
    description: event.target[0].value,
    time: event.target[1].value,
    isComplete: false
  };
}

Questions:

• How bad is the default behavior?
• What if we leave it there?

See: #10