Isn't this a time bomb waiting to explode regardless of a federal shutdown?   

There have been a few temporary food stamp programs from the Great Depression through the 1950s, but they were limited in scale and funding was minimal.  It wasn't until LBJ's "Great Society" project in 1964 that food stamps slowly became a permanent mainstay of American life.  By 1969, food benefits were in full swing, yet, only 1.4% of the population used them.  Strict eligibility requirements kept the participation rate down until 1977.  

Candidates had to have a gross income below the poverty line.  Their liquid assets (including vehicles) had to have limited value.  They had to put some of their own money into a portion of the stamps in order to get the "bonus" stamps.  Able bodied adults without children were largely excluded. College students and immigrants were barred from the program.  Able bodied adults had to work or be in training.  Monthly income and expense verification was required. Food stamps were paper, creating a "shame factor".  Just because someone was under the poverty line did not mean they could qualify.

Most of these barriers have been absent from SNAP in the past few decades, which is why the percentage of users spiked from 1.4% to as high as 15% of the population.  Today, the rate stands at 12.5%, which is still extraordinarily high.  Approximately 19 million SNAP users have been on the program for longer than a year, and over 80% of people on the program are able bodied and below retirement age.

In other words, the program has become a crutch for a vast number of people who do not need it.

The most common argument in favor of expanding food subsidies is:  "What about the single moms?"  Around 25% of all SNAP users are single mothers, and yes, it is increasingly difficult for these women to work full time without child care.  However, while there are plenty of cases of desperate moms in need of a boost in times of hardship, there are also endless cases of abuse of the system.