What´s the difference between "strong" and "weak" moral values? Maybe you are you confused with the difference between authoritarian/intolerant values and liberal/tolerant values, but the latter are just as strong (or as weak) as the first. Nobody favours a society without values because that would be impossible, and because that would be a value itself.
Weak moral values mean that you consider having a child out of wedlock to be as valid a choice as having a child inside marriage, despite what we know about all the financial and psychological disadvantages that children from single-parent homes suffer.
You're right that having no values is a value in itself, and this is the value that many liberals preach.
Liberals often preach individual freedom with socialized responsibility, meaning that people can do whatever they want, and pass the consequences of their actions onto society at large. This has become the bedrock of modern liberal philosophy. It will never lead to anything but more problems.