I personally hate the idiom “living at home” to mean “living with parents” but that’s how it’s used by many
Which leads to my next question - why is cohabitating considered such an indignity?
By choice it’s no indignity. The problem is when you do it because you are forced to by economic circumstances. Lack of freedom.
It's what the living situation communicates about the type of job. Higher quality jobs (or maybe higher savings rates?) generate enough resources and momentum to progress through the life stages of living independently and forming a household apart from the parents.
Higher quality jobs (that is to say, jobs requiring skills or credentials that in turn require substantial advance investment of time and/or money) are one factor. It seems to me that the author is trying-- but unable-- to articulate something about the serious barriers to entry into the kind of job that will provide that level of resources and momentum.
Barriers to entry include credentials, experience, connections, logistics, and external support. These barriers are real and not all of them are self inflicted. The writer's error is blaming all of these barriers on the employer.
With regard to credentials, I've seen serious credential inflation in most jobs, including caregiving, construction, and maintenance. Most call centers, schools, and transportation companies-- for example-- require a high school diploma or GED as a minimum condition for hiring people to do janitor, driver, or customer service work. But the jobs don't come close to requiring that level of education. In these cases, the credential is an artificial barrier to entry. I've heard it said that the bachelor's degree is the new high school diploma, and judging by the amount of remedial work required in the first year to compensate for the lack of preparation for college or university level work, I think it's an accurate statement. Companies require high credential levels because they can. But the time and money required to get a university degree is exploding.
The experience barrier is the not-well-articulated problem the article writer is trying to describe. To get a high quality job in today's economy, especially without a STEM degree, you generally need several years of experience. People start out in an entry-level job like the one the article writer had, and then rack up enough time and experience to qualify for a transfer to something that pays better. But the only way to get experience is if someone will hire you, or if someone will support you financially during the entry-level years, or if you pick the kind of job where the sort of work experience you can get as a student is relevant or valuable to the employer. People like the article writer, who focus on school instead of racking up work experience or who are financially unable to work for free at an "internship" for months at a time, often find themselves shut out of the desirable jobs because they graduate with little to no relevant work experience. They have to settle for entry-level jobs, which means they must either subsist at a very low standard of living that is well below what their upbringing and class expectations have taught them to expect... or they must be financially supported by somebody else such as a parent. A person who follows the conventional advice to move to a new geographical area has no such support system, which leads me to the next barriers.
Connections are how people tend to get jobs coming directly out of school. The school might have an established relationship with the employer, or the new employee might have been in a position to work an unpaid or low-paid internship. Logistics also favor the in-crowd. If you have multiple family members and friends to team up with, it's relatively easy to find a single room to rent in a safe household. If your family has lived in the Bay Area for generations, there are multiple potential safe places to sleep during the low-paid entry-level years or if the job you've trained for just doesn't pay much. At least some of them will be close to public transit so that the new employee can avoid expenses such as vehicle expenses. Being able to live with a parent or relative is a great way to avoid debt. But it's not the employer's fault if the new employee is from out of state and if he or she does not have a support system. It's also not the employer's fault if the new employee is not willing to accept a much lower standard of living than he or she enjoyed as a student or as a dependent of a more established person.