A younger person shouldn't max out their 401k unless they are rich. When you are young time works for you and so a maxed out 401k is a very large retirement in the future (which you might not even live to see!). The max is useful for older people who didn't start young.
This is bad advice. Max out 401k early. Compounding growth is how you get rich / FI. The earlier you start, the more time to compound.
Worst advice ever. Maxing out early is like throwing a boulder down a mountain as opposed to a stone. The sooner you start the better in the long run.
What they have to avoid is cashing it out when times get hard.