Yes, it's true that it's probably possible to get a couch without going through a RTO contract if you have the money to make RTO payments. That doesn't mean it's reasonable, plausible, or even just worth all the extra effort. If you need a couch now and can pay it off a few payments down the road, it's not so bad to be willing to pay a substantial expense for that convenience. As long as the consumer is informed, there's no reason this voluntary trade of security/convenience for money shouldn't be allowed or performed.
Of course it'd be cheaper if the consumer had access to cheaper credit, but they don't, so these places have sprung up to help/serve those people. Again, I don't think there's anything inherently wrong with that. It's just expensive (for both parties).
I know because I was doing exactly what some people in this thread would suggest. We moved to a new house Wednesday and needed a gas dryer instead of electric. Though we could afford the $2k for a nice new set, I looked around and found a great deal on a barely used pair that an elderly couple had to put in storage when they downsized. I rented a Home Depot truck while movers were still loading up at the old house, met the folks at their storage unit with their son to help me load it, got the W/D loaded up, and brought it over to the new house while the movers were still there so that they could unload and hook it up. I ended up saving about a thousand dollars and helped out some nice folks who were happy to not need to pay for the storage unit anymore.
You're right about the insurance and valid license being a requirement for a rental, of course. Around here, that's a pretty low bar because almost everyone drives (and I'd bet the people in the article drive too). I could see that being an issue in places where public transit was half decent and people didn't drive. On the other hand, a fair number of people in blue collar work (like at least the one guy in that article) have easier access to work trucks than most of us.
I'm well aware of and thankful for how privileged I am to be able to maneuver without as much financial pressure as the people in the article. On the other hand, if my time was only exchangeable for minimum wage, saving four figures would be well worth the time and effort of arranging something like a Craigslist purchase.