right. if you have an emergency, an operator can tell from three tower points what neighborhood your cellphone call came from, but not the exact location. the only way they can find that out is by going door-to-door and asking if anyone needs help.
when you call 911 on a landline, your exact address can be traced and medics can be dispatched immediately. so, even if you never use it, the cheapest land line is not a bad thing to have around, especially at a 'certain' age or for anyone with health issues or small children.