It never really did, nor was it ever intended to do that. It's always been a wage that was at or slightly above the federal poverty line.
The lowest minimum wage I remember hearing about as a kid was $1.50/hr. I thought that sounded like a lot of money at the time, but I probably was not even 10 years old.
That would have been in the first half of the 1970's when the federal poverty line was around $2,500. So working full time, you'd make $3,000 or about 120% of the poverty level.
Today, the federal minimum wage is $7.25 an hour and the poverty level (2016) is $12,200. So still, a full-time minimum wage worker earns nearly 120% of the poverty level.
