This is why everyone wants to be university educated. The great bulk of "respectable" office jobs require no real skill or effort, just some cultural knowledge about how to talk like you're contributing.
AKA people invent novel ways to support themselves when the alternative is starving in the street
Some non-productive people are non-productively lazy, and UBI may work for them.
Others are non-conformist creative types, and UBI will half work for them. IMO it's good to have some of these types around in a business to shake things up - as long as they have some practical skills and aren't just dreamers.
Others are primarily interested in accumulating power, and corporations provide a perfect cover for them. They will get off UBI as soon as they can, but they're often incredibly toxic, and large organisations of all kinds are very good at empowering them.
With the odd exception, they're probably the biggest threat to the future of any business. And they're very good at disguising this. They're the people who turn in solid financials and performance stats. But the results are built on rubble, and often their management doesn't discover this until it's too late.
So your observation reminded me that our society has plenty of people on a similar sort of hidden dole: vast corporate structures with uncountable layers of non-productive paper pushers, with a very small proportion of employees setting the vision and another small bunch generating most of the value. A social welfare program by any other name ...
So like do large human groups just inevitably have some subset that doesn't quite fit (in terms of work and productivity) but who need taking care of so we semi-deny their existence ("no slackers here!") while we semi-throw'em a bone ("here's a paycheck, go look at Facebook for a few hours and fiddle with PowerPoint while I harass my secretary")?