It's a myth, perpetuated by the credit industry, that credit is even necessary.
I have no credit cards, and have nearly paid off all my other debt. Once finished, that will be it for me. The only "livable" credit for me, is a mortgage, and in reality, having a great credit history for a mortgage loan is less important than most think. Length of time at a job, current income etc, outweigh a good credit score any day of the week.
As for using credit cards for an emergency, that's a dangerous situation. Ideally, you should save 3-6 months of income and THAT is your emergency fund.
There have been a serious of interviews with the millionaires across the country, and the overwhelming majority say the primary reason they have remained millionaires is by staying out of debt.