If it's defined as only having access to an income below some percentage of the mean (or even median), it has some value, though it's certainly debatable how much. I'd be more interested in measures that looked at what percentage of people remained in poverty for most of their lives. If poverty primarily only affects, say, people who have just moved to a wealthy country, but they're all able to climb out of that state, then it's reasonable to conclude there's no longer any significant poverty problem as such.