I'm a bit ignorant of IBMs business model given how many times they've changed businesses. What you're saying is that IBM has a business that generates revenue, but that business continues to exist (and generate revenue) despite people not actively being at a desk, not that IBM has somehow managed to find a way to make money from empty desks, right?
WeWork makes more money from an oversubscription model, and thus could also make money from desks being unused. (Have 10 desks, rent out "13", and hope that all 13 people don't need desks at the same time).
What I don't understand is the multiples at which WeWork was trading.
I could definitely understand the business model (it's cloud computing for real-estate!) and especially cool for remote/business travelers since from what I understand it was rather easy for a WeWork user to use any of their facilities.
It's more that they bill by the capacity used and it's possible to cancel at any time.
Same way a WeWork is more expensive than renting your own real estate but it's probably simpler than getting into a long term lease. Plus if your startup has to scale up WeWork can accommodate, unlike your typical office rental.