On reddit at least, I suspect that it's because the average poster there is sheltered and middle class. They've got enough class based guilt that they'd never dare question someone who states that the reason for something is due to being poor. Though part of it is also due to the middle class in general just buying their way through what should be some basic life skills. A lot of middle class people just can't grasp that poor people might be better at some things than them. So if their middle class selves can't cook properly and they need to buy everything packaged, then obviously that's the case for 99.9% of the population.  Then again, I was once told by someone on reddit that my ability to cook was an example of "poor privilege". So who knows.