I work for a private company, with no pension, but we do both. We max out our 401ks, because....why not? Tax savings, employer match, and access to great investments (mine is even through Vanguard) means it is a no-brainer.
If we need to access that money before I am old enough, I will do SEPPs. Otherwise, we continue to invest in Vanguard account to help fund FIRE. Our current plan is to retire when our FIRE money (not 401ks) is enough to replace income. This plan is super conservative, which gives us flexibility to retire even earlieer, go part time even earlier, etc, if we can't wait the 10 years :)