Oh, am I. Yes, economic necessity can be a diversion, and it's important to ensure you don't get trapped by said diversion. But to think you can't learn anything from being diverted is foolish. You can, and you can leverage that experience in a variety of ways so in that sense it is not a terminal disaster.
Actually, I do work in a highly competitive industry of the kind you describe, the film business, and networking and word of mouth does matter. And I've done a lot of free work to get a toehold in it - in that sense, my comments were far too general and therefore wrong. On the other hand, those were mostly cooperative ventures where everyone was working for free or nominal payment.
Let me rephrase: unpaid internships at well-established, highly profitable companies are a scam. If you can afford the risk of having a clueless newbie around, you can afford to pay them minimum wage. If the work needs doing, then plainly it has some economic value. So does the learning environment for the intern, but that doesn't pay the rent while they're working for you. Landlords, retailers etc. aren't in the business of giving the first one away, they tend to request money up front.
It's not the shitty menial work I object to, mastering those tasks with a smile is an essential quality in many industries. It's the willingness to exploit people when you can afford to pay them without any significant cost to yourself. Shitty menial work on internships does filter out people who can't get shit done, have an entitlement attitude etc. Unpaid internships filter out anyone anyone who doesn't have a financial safety net, regardless of their skillset, motivation, or potential benefit to your organization. Working a second job for that period can be impractical, considering that the eager intern wants to give 110% to show off how great they are.
Is it really too much to ask that in return for such a commitment, someone should get paid enough to afford food, laundry, transit and a bed to sleep in?