The flip side here is if the large company goes belly up - like Kodak did - the "outsourced janitor" might still keep their position at the company they are working for - they will end up working at another customer location.
Outsourcing is about reducing costs. It's not good or evil. But it depersonalizes decisions on which service to choose and narrows the decision making criteria down to cost. Costs for service jobs are driven by people. So, when a company is choosing their janitorial service and they choose the lowest cost service, that means the service that pays the lowest wages or that cuts the most corners will typically win the contact.
Depersonalizing the buying decision and commoditizing human labor aren't good or evil by themselves. But, turning people's welfare into a math problem certainly leaves us open to making decisions we wouldn't have made if we saw the consequences through a human lense instead of only an economic lense. At best, it causes suboptimal outcomes for an individual while maximizing the aggregate benefit.
We can fight against it all we want, but everytime we buy a t-shirt, an apple, or an iPhone, there's a supply chain behind it built on the lowest cost provider. We are all part of that process. I hope I'm not evil for buying a cheap t-shirt. But I know I enabled some shady behavior that made it $1 cheaper.
sure. but it's a potential option as opposed to being let go flat out.
If Kodak went belly up before that "rags to riches" story of a janitor becoming an exec proceeded beyond the janitor stage - she'd be looking for another job elsewhere, whereas in contractor's case there's a chance of getting reassigned to another "project".
It's not as much about "depersonalizing" as it is about convenience of not having to deal with the domain that has nothing to do with core business. The cost factor is also not linear - in terms of straight up cash figures sometimes it costs the same or more to outsource maintenance, security etc vs hiring your own.
Works both ways - car dealership for example isn't going to hire a web designer for their site full time.