I think this is NOT good advice. Reasons:
* the more you invest in your 401(k), you reduce your tax bracket
* you can invest more money since its pre-tax. The caveat being here that you will be taxed when you withdraw. Usually its a worthy tradeoff
* you still have the option of directing your money in Vanguard or Vanguard like ETF's since you are in control of where your 401(k) money goes
IANAL so let me know if what I said is factually incorrect.
Reducing your tax bracket isn't meaningful separately from the next item; the idea that it is comes from a misunderstanding of progressive taxation.
> you can invest more money since its pre-tax. The caveat being here that you will be taxed when you withdraw. Usually its a worthy tradeoff
For most people, yes (probably, though obviously this depends on future tax policy and other future events), but this is not universally the case.
> you still have the option of directing your money in Vanguard or Vanguard like ETF's since you are in control of where your 401(k) money goes
Depends on who your employer has managing the 401k and what they offer. This varies a lot.
You're supposed to have your emergency fund completely built up before you save for retirement.