Why a process model is important?

$1-$Software development can become chaotic without the control & organization offered by a defined process.

$2-$As stated in previous chapters $,$ a modern software engineering approach must be $$agile$$ and embrace changes that are needed to satisfy the stakeholders$$ requirements.

$3-$It is important NOT to be too focused on documents and rituals.

$4-$The process should only include activities, controls, and work products that are appropriate for the project team and the product that is to be produced.

What is meant by no$.2$ and $4$ please. Thanks