That is an old industry proverb. It perhaps has it's origins with Voltaire - "Il meglio è l'inimico del bene" > "Perfect is the enemy of good".
Modern society sometimes forgets this. Nothing made by humans is perfect or can be. There are three fundamental reasons for it:
1) You can always improve something. Don't take my word for it, look at the mousetrap industry.
2) Not everybody agrees on what "perfect" really should be.
3) The systems surrounding a project are changing so the perfect list of features is dynamic. Some become unnecessary, and new ones must be added.
FSD is a project so it cannot be perfect. So we need to define what 'good enough' is by law. Tesla is a company that seems to understand this more than most. People complain about the imperfection of Autopilot when is the best driver's aid for all conditions for sale today.
The Autopilot crashes are unfortunate, but are to be expected. The fact these are generating lawsuits is detrimental to the goal of better automotive safety. The lawsuits are based on the premise that AP is good, but not perfect, and Tesla knew that and should have only sold something that doesn't exist nor can ever exist.