My naive view is that it's similar to the reason some companies use AWS rather than running their own data center. That is, it's worth it to pay the premium to not have to manage their own space, and have the flexibility to scale up/down their usage a bit more quickly than locking into multi-year leases.
Real estate is a real pain in the ass for small startups; it eats up like several man-months of companies that have no people dedicated to stuff like this. I do think wework is bullshit, but thinking back to the process of moving a company your point makes sense. And in earlyish-stave companies the CEO / bigwigs are most involved with moving and corporations' decisions are no more economically rational than those of the people in charge.
WeWork is better than opening a satellite office in pretty much the same way that renting a hotel room is better than buying a house in a location that you're visiting.
Once you've proven you have traction and it's going to be sustained, it makes sense to transition to your own real estate (owned or leased), but in the early days, it's better to wildly "overpay" for temporary, flexible, easy space.
WeWork, at least in my area, has also picked office spaces right next to metro stations. This real estate is hard to find and several of the companies working out of WeWork advertise how they're located right next to the metro exit.
I'm just saying that this entire community feels very bearish on WeWork, but there is some method to their madness
Office space is sort of a commodity, though there's a lot of friction in lining it up. But the thing about datacenters is you need three with independent networks and power and cooling, and that's crazy expensive before you can actually fill three halls.