I think the author is giving VMWare too much credit. VMware were late to market with a web interface (Flash) and when they did release it they'd based it on obsolete technology.
The Flash interface was VMWare's first web interface. Prior to that we had to use the Win32 client. And for a long while the Flash client still couldn't do everything. For once thing it was vCentre only. You still had to use the Windows client to manage individual hosts. Also VMWare tech support often told you to perform tasks with the Windows client rather than their Flash web UI.
But even whilst VMWare were working on the Flash interface the writting was already on the wall for Flash so they were working on a deadend product.